In what universe would adding line-breaks to a giant run-on paragraph be considered offensive? I can't imagine being that worried about offending people that I'd put an apologetic disclaimer on a reformatting of an internet comment.
As a bilingual non-western national, I find the disclaimer respectful and appreciate it! FWIW, I would not have been offended per se, but would have been mildly annoyed without it.
I grew up with a family member who spoke (and wrote) Hawaiian pidgin. His emails would be like, " Eyyy! Me an bruddah Brent goin to get plate lunch. You want?"
Obviously, his Hawaiian vernacular was an important part of who he was, and retyping that could change the identity of the speaker, e.g., "Hey, my close friend Brent and I are going to pick up some Hawaiian take away lunch. Would you like me to pick some up for you?"
Now, not all folks are that attached to how they write, or may be self conscious about their English and really appreciate the corrections.
Hence, a gentle warning and note that if the author is bothered, they'll remove it seems just about right. It's extending a courtesy to the author and saying, "please assume I had good intent!"
By the way, good on you Michael and best of luck in the future.
Seems weirder to be this bothered by a harmless disclaimer, tbh.