because he actually did nothing about it until he was fully involved.
i.e. until he was ~50 years old, when he stepped aside
his words (Sun, 16 Sep 2018):
This is my reality. I am not an emotionally empathetic kind of person
and that probably doesn't come as a big surprise to anybody. Least of
all me. The fact that I then misread people and don't realize (for
years) how badly I've judged a situation and contributed to an
unprofessional environment is not good.
[...]
I am going to take time off and get some assistance on how to
understand people’s emotions and respond appropriately.
Which is the same things Stallman said after they tried to push him out.
Linus is just smarter than Stallman, was preoccupied at the time that Linux development was being taken over, and released a public statement that made people happy, bu also he haven't changed much [1], because, in the end, he is who he is and we should appreciate him for what he's achieved.
[1] a year later he released this statement
people take me seriously in a way they didn't do back in 1994.
And that's absolutely not some kind of complaint about how I wasn't taken seriously back then – quite the reverse. It's more me grumbling that people take me much too seriously now, and I can't say silly stupid crap anymore.
So I'll still call out people (and particularly companies) for doing dumb things, but now I have to do it knowing that it's news, and me giving some company the finger will be remembered for a decade afterwards.
Whether deserved or not, it might not be worth it.
He realized that people were trojan horsing his words against Linux.
But he's Linus Torvalds, he's in the unfortunate position of being the face and image of the most successful OSS project ever, not some guy on a mailing list about Thunderbird, that nobody cares of.