Yes, it is offensive to them, because no matter how much they scream, cry, and coerce others to play along, the one thing they can't do is change that xy to an xx. Menstration, pregnancy and childbirth are all things they can't cheat. So they must denigrate them and women, to lessen the harm to their delusions and feelings.
Said delusions of the troon crowd run deep. To quote one of the orbiters from that post, "Dude, if you want to be a woman, it takes a huge commitment and investment but it absolutely can be done. And as the science evolves, it will get easier, we'll reach the point where gender reassignment can be done with pills."
First off, I don't give a shit if you want to portray yourself as the opposite sex. If you're an adult and you're not hurting anyone else, then knock yourself out. However, to claim "it absolutely can be done" in the sense of "everyone will believe that a man in a dress is actually a woman" is utterly laughable. In the overwhelming majority of instances, bordering on 100%, your brain registers something off about a troon. Even the most progressive minds out there will still immediately spot a troon, no matter how many times they try to train themselves not to. No matter how much time and effort you put into it, you'll never be able to fully hide the characteristics that XX or XY chromosomes impart. For the ultimate example of this, look no further than Jazz Jennings: raised as a girl, chemically castrated, pumped full of female hormones, fauxgina installed, and at the end of it all still looks obviously male. That's to say nothing of all the lazy-asses who put on a wig and call it a day.
As I said, if you're not hurting anyone, you can do whatever you like with your life. I might question whether it's the
right thing to do, but I won't stop you. But when men start barging in on women-only spaces and demand to be recognized (and vice versa, though I'm not sure how often that happens), that's where I draw the line. You're not a woman, you never have been, you never will be. These spaces are segregated for a reason.
And to that further point of The Science™, it really does show how these people treat it like a religion. Pray to the almighty Science and it will bestow free gender reassignments and hovercars unto you! Never mind that there are countless aspects of biology that we still don't understand, that gene editing is still in its relative infancy, and that fabricating a whole X or Y chromosome out of the other is far beyond our current reach, to say nothing of how the body would react if every cell's genome was replaced. Nope, one day you'll just take a pill and bam, woman!
I mean, I'm not just going to discount the possibility altogether, because I'm not able to see what the future holds. But even if we reach that point decades or centuries from now, remember, at the end of the day, you were always born either a man or a woman. Even if that magic pill that turns you into the sexy anime babe of your dreams exists someday, it won't change your past. You'll never have that lived experience of a woman, something that's really important to this crowd.
Anyway Bob's an idiot, and his profile pic is the only rebuttal to his nonsense you ever need.
@Positron (seriously Null fix your damn quotes):

Did...did someone cosplay Andrew Dobson's character?
For those unaware, Squirrel Girl is a joke character from Marvel's canon, in that she has a goofy power (squirrels) but defeated Doctor Doom in her first appearance, so the further joke was that she was actually more powerful than she seemed to be, or something along those lines. She appeared off and on for a couple decades until Marvel rebooted her in the guise shown on the bottom right, turning her from relatively-normal looking to a chonky derpfaced retard. The art wasn't good, but the writing (by Ryan North of Dinosaur Comics "fame") didn't help either, where he took the joke absolutely seriously and wrote her to be effectively the most powerful character in Marvel canon, palling about with Galactus and the like. The series had to be rebooted almost immediately, but I didn't even bother to look into it after that. Apparently they changed artists a couple years ago too.
At any rate, this interpretation looks closer to the original concept, so it looks like the TV/film side of the Marvel business continues to have a better understanding of what people want than the comics division. What a shocker.