Look, JupiterAsc, just because I cook dinner for my husband and me doesn't make me a professional chef.
As I indicated above, academics oftentimes apply their field of extertise to other topics, in a cross-fertilization and even cross-disciplinary kind of way. Then most fields are internally varied. Classical studies is a huge field, so we find its scholars writing about Greek and Roman philosophy, poetry, governance, religion, trade, and what have you. This doesn't mean classicists are ticketed philosophers, poets, theologians, economists, and so on. Then linguistics is its own field, oftentimes taught in anthropology departments. So for a classics professor to write about mathematics in antiquity doesn't make him a mathematician, unless s/he also practices mathematics or has an advanced degree in mathematics.
I wouldn't think any of this matters, except that if a given author has a graduate degree or two in a particular field, let alone if s/he has taught it as a tenured professor at a research university, it does indicate a certain level of expertise in research methods that the average astrologer cannot match.
I don't think the average person is aware of how high the bar is for the permanent university faculty in research institutions. In the US and Canadian systems, a Ph. D. is the minimum admission pass to employment, which occurs at the untenured assistant professor level. Ever hear of "publish or perish"? Faculty at research universities are indeed expected to publish their research. In order to get published in academic journals and most academic book publishers, there is a double-blind peer review process and the most prestigious journals and book publishers have high rejection rates. The academics' work may be further criticized in the literature and professional society conferences by other experts in their field.
In most fields today, faculty are also expected to write grant proposals and have a decent success rate in attracting external funding in order to fund their research and their grad student advisees. (And in some fields, post-docs.) Some of these grants are also highly competitive.
Then faculty undergo annual merit reviews, and the newer faculty face a brutal tenure process around year 6 of their appointments, with additional external experts scrutinizing the quality and quantity of their research and with three in-house panels of peers reviewing their files. Some of the assistant professors don't make the cut, and then they have to look for another job, whether within or outside of academia.
If these faculty members do get tenure, they get job security and a promotion to associate professor rank, but the research and writing process continues, with their colleagues heaping scorn upon any Professor Deadwood who fails to keep up this regimen. In mid-career many faculty undergo yet another round of serious internal and external evaluation of their body of research if they seek promotion to full professor status.
All of this research work occurs on top of teaching classes, individual student advising, committee work, and oftentimes administrative appointments.
So while the average professor normally wouldn't know as much about astrology as a professional astrologer would, the scholar would normally know a heck of a lot more about research methodologies and his/her own field of relevant expertise, be it Latin or mathematics. S/he would probably have rigorous standards for presenting facts, simply because s/he is so used to constant critical feedback from experts in the specialized research sub-field. [The one exception here is the scientists' uninformed lampoons of astrology, but I don't think you will find this in the humanities. We also have to distinguish between scientsts writing popular pieces vs. advanced physics or chemistry for their peers.]
Moreover, the astrology basics are not that difficult to learn. Translators of ancient texts will often seek feedback from other experts prior to publication, in any event, to develop the best possible translation.
This is why I get annoyed sometimes if I read an astrologer's post or article and find him assuming things about the past that are simply incorrect, or making blanket assumptions based upon the slenderest kind of evidence. Normally I don't hold astrologers to academic standards, but occasionally they develop a whole belief set about the past that really needs some kind of scrutiny.
I also find it fascinating that some older, well-established astrologers decided to return to accredited universities to earn their doctorates: astrologers like Robert Hand, Liz Greene, and Nicholas Campion. I think they figured out that there is a bigger league out there than the closed-in xenophobic, "they won't understand us anyway" world inhabited by some astrologers.
Do I make mistakes in interpreting astrology's history? For sure. Hopefully we are all here to learn and correct any misconceptions. This is exactly how the give-and-take of dialogue furthers the advance of knowledge.