You're right, I'm cis. I mean, no, no one can decide for someone else what they are offended by, you're right. But when you have a show embracing all sexual/gender types and only mocking the intolerant, it's hard to take that outrage seriously. To me, it's like someone protesting that the Three Stooges endorses bullying/abuse. It isn't even clear if trans people in general are bothered by the term transsexual, or if only the vocally active group thinks so (and do they get to be the barometer?).
So, yeah, anyone can be offended by whatever they want. You really can't control what offends you. If you are offended, you're offended. And I can decide I consider their offense misplaced. I mean, I'm gay, but there are things people say/do I find offensive relating to gay identity that other gay men don't find offensive at all, and would tell me to get over myself. And it's as okay for them to have their response as it is for me to have mine.