Wow, it didn't feel nearly that sloppy when I wrote it, I swear! Thanks for debugging me. Now for the politically incorrect explanation of my thought process...
I think when constructing the argument my brain actually substituted "women I sexually care about" with "women". How horrible is that... For (hopefully obvious) reasons females who sexually interest males are far fewer that males who sexually interest females. Does this seem acceptable to you? As you stated, it's easier for men to upgrade their attractiveness, and this can be true for men well in their fifties and older.
If you check closely I didn't say that men typically claim the moral high ground more often that women do, just that they can appear to have it for the (ridiculously flawed) reason I originally stated.
I wonder if my thought process highlights some mind killing aspects of this topic, and honestly I'm not sure anymore if the improved argument is much more plausible.
Information that surprises you is interesting as it exposes where you have been miscalibrated, and allows you to correct for that.
I suspect the users of LessWrong have fairly similar beliefs, so it is probable that information that has surprised you would surprise others here, so it would be useful for them if you shared them.
Example: In a discussion with a friend recently I realised I had massively miscalibrated on the percentage of the UK population who shared my beliefs on certain subjects, in general the population was far more conservative than I had expected.
In retrospect I was assuming my own personal experience was more representative than it was, even when attempting to correct for that.