I'm sorry, can we read those back again?

First comment: “My 30 seconds just isn’t going to cut it.” -> Clearly a man

Second comment: “That’s why you have a mouth and hands, potentially even getting your thigh in there. Honestly, the penis in the vagina is sometimes the least exciting part about sex with that arrangement of genitals.” -> Telling a man that PIV is not the only thing to do, but that he should be putting in more effort than just offering a penis

No, that says "there are other ways to have sex than PIV," it does not say "you should be putting in more effort "

Third comment (my comment): “The same is true the other way round too. Which makes it all the more frustrating that a lot of women think their whole contribution to sex is to lay there and provide a vagina.” -> Telling women that PIV is not the only thing to do, but that it would be cool if they too put more effort in than just offering a vagina

Your response to a woman saying "there are other ways to have sex besides PIV" is "it would be cool if women put more effort into sex." You're telling this to the woman who is saying there are other ways to have sex besides PIV. All she said was "you can use your mouth, too!" to the guy making a joke about lasting 30 seconds. Nowhere did she say anything about men at large. Do you think this is some competition between men and women so you had to throw in to say "no actually women are worse?" Do you genuinely not see how what you said in this context was totally uncalled for and sexist?