When I see an out of sign conjunction there are a few things I look for to determine if it will ‘work’ as a true conjunction. Your Moon/Mercury passes my 4 basic requirements.
First I look at tightness of orb. If it is a very wide conjunction, and out of sign, then it is greatly weakened, in my opinion. I like it to be 4 degrees or less for strongest impact. Yours is on the edge of that. However, it passes the other 3 ‘tests.’
‘ Are there aspects made to both planets from another planet? ‘ You have Saturn and Pluto making aspects to the conjunction. That tends to unify the two planets in conjunction.
‘ Is there another point, planet or angle in between the two bodies?’ Your North Node is in the middle. That is another thing that can unify two planets.
And, perhaps most significant, the Mercury is the ruler [dispositor] of the Virgo Moon. That also cements the two planets into a unifying role.
So, in my opinion, your Moon and Mercury conjunction is valid, even though it is ‘out of sign.’ They probably work in unison to give you an active mind, great powers of perception, and an active imagination with intense emotional reactions to injustice?