It seems like the age of consent is political, or the age would be identical everywhere.
There is a bell curve for the start of human sexuality. Here in Sweden the age of 14 is the median for girls, 14.4 for boys, and the age of consent is set to 15. Does that mean 15 is a good age of consent? Should the age of consent be the median age, the 10% (12y), or the 80% (16y)?
Personally I prefer the "half the person's age + 7" rule (for the partner's minimum age), but I don't know any country that has that as an age of consent.
A similar argument could be made about driving. At the age of 16, the impulse control is severely underdeveloped, likely by evolutionary benefits. New experiences invoke a much stronger endocrine response than for fully matured individuals, and with faster depletion rate. A driving license should really be around age 20+ if one would follow mental maturity. Sweden have set it to 18.
We have so many different age lines. Driving, drinking, military service, voting, consent, crime, legal responsibility. 25 would be a great line for it all based on medical data. In Sweden we expect young people to have the mind around 15 to start having sex with each other, but we don't trust that they have the mental capacity to drive before 18. Is the numbers that the US use better? Worse? Is the answer political? I would say yes.
By that rule (guideline), a 50-year-old should not be in a relationship with an 18-year-old, even if 18 is the age of consent.
Now I don’t have an opinion on how great or terrible the guy is but if 50% of the country supports him, then that’s indicative that there isn’t really any consensus on age differences when dating.
Personally I think there is no reason to look down on consensual relationships between two adults. Especially true if they are far beyond the age of consent.
Having said that - the issue at hand right now is whether RMS should or should not be on the GCC steering committee, not managing the FSF. And "leadership" is an even more diffuse term.
Also, one should bear in mind that Stallman has (AFAICT) Asperger's syndrome or High-Functioning Autism (a.k.a. neuro-diversity). That does not excuse much in itself - and in fact, is an argument against making him a powerful singular boss of people - but should be taken into consideration when you think about how this sort of situation develops.
The FSF is a startup that never grew beyond the "scrappy entrepreneur in garage" phase. Starbucks has a much better chance of surviving collective action than your average neighborhood kombucha café place.