I believe he need to keep on repeating the same things over an over since
people to not seem to understand:
rms is not against "commercialization of software" (he is against
proprietary software and clearly says, in this interview, that the
distinction between free and proprietary software has nothing to do with
commercialization);
he does not "take credit for Linux" (he clearly says, in this interview,
that Linus Torvalds is at the origin of the kernel and decided, after some
time, to distribute it under the GPL, hence filling the last remaining hole
for a free operating system);
he is far from having a "get off my porch" attitude (he invites everybody
who values his freedom to embrace free software).
As for your impressions on the form, they are your own. I do not find him
"aggressive", "angry", "bitter" or "cranky". He only defends his ideas.