Penders is
completely unrelated to SEGA targeting a slightly different public than before (only slightly, because even the darkest they did was familly friendly and pretty tame). The most he have affected for the game is certainly having helped sending Chronicles down to oblivion, but even that might not be 100% is doing.
He also have nothing to do with the cancellation of SatAM, it was mostly a problem with the channel. The most he did about that is that he made Ben Hurst have even less chance to do his movies, by painting that Ben Hurst wanted to be hired by SEGA to do that in a not really charitable way (according to Ben Hurst himself), but even that was nearly doomed to fail, because that's not how licencing part, you aren't paid by SEGA to do Sonic stuff (except if you are working on SEGA projects, of course), you pay SEGA for the authorization of making Sonic stuff.
Even on the comic, he isn't related to most of the "mandates" (that often are just rules that SEGA that their official comics should respect their vision of their own IP).
Ken Penders mostly harmed the comics and his own reputation. He have had a lot of problematic behaviour, but he didn't and still doesn't have the power to change that much stuff outside of his work… which is now nothing as he burned every possible bridge. And for me the biggest proof that he doesn't have influenced the games to become less "serious/mature" is that… the change of tone started with Unleashed, and continued with Colors that both were dev and released before the lawsuit.
So no relationship with the lawsuit.
Sonic is family friendly because they target a young-teen/pre-teen public, as they do that since basically forever. Even the "darkest" stuff like SA2, Black Knight or even Shadow was really clean and not that "mature". The fact that Shadow and 2006 where heavily seen as the worst thing ever didn't help to see that it was a way worth going to.
I won't say that there isn't any writing problem (For me IDWSonic and - ironically - the Sonic Channel stories shows how it could become better on some aspect), but the question is for me not just "they made it for kids now it sucks".
I don't care about Penders' claims. Besides, if SEGA can't do serious stories with Sonic, because heck they still have it in their hands, they should sell the IP to another company like Atlus, for Atlus to add a lot of things that SEGA couldn't do.
SEGA have absolutely NO interest in selling their best selling IP just because some people on the internet (thus a small fraction of the actual buyer) want something. There is no "they should sell it", why would they say one of the thing that help them keeping in a good shape ?