I've experienced saturn on someone's mars and pluto on someone's mars, and they didn't feel to me like what you described. Saturn on someone's mars was me disapproving of them being overtly sexual, or even vulgar in my opinion, because I felt inadequate, while secretly wishing I could be more like them, pluto on someone's mars has been more neutral, simply being able to see how their mars works when they are attracted to other people.
Two things occur to me as being possible causes for your reaction, neither of which are astrological. The first is our automatic reaction to people who are weak. I recently saw a TV programme about a penguin rescue centre in South Africa. People found a penguin wandering around on the beach and they realised it was blind, so they brought it to the rescue centre which housed rescued penguins before releasing them back into the wild, but the other penguins all turned on the blind one! They realised it was blind and couldn't stand up for itself, so they attacked it. Perhaps it is a throwback to an earlier evolutionary state where we don't want to have to support the weak. The way to overcome this, in my opinion, is to have compassion for these people, and we feel much more comfortable ourselves when we are focussing on compassion rather than disgust, so it's a win-win solution.
Another possibility is that he has said something slightly suggestive to you, perhaps just flirtatious or an unsophisticated attempt to be charming, and he is not your type for so many reasons other than astrology, for example he is the wrong age, and you are worried that you do not know how to rebuff him or make it clear to him that you are not interested, so you are worrying about the situation and that worry is an uncomfortable feeling, so in your mind you link him with an unpleasant feeling. If this is the reason the best thing to do, in my opinion, is to avoid him, to make it clear to him that of course it isn't even a question that you would be interested in someone his age, to let him see how you behave around people that you are interested in and to compare how different it is to the way you behave towards him, and to just put him out of your mind.
Sorry I can't be more astrological.