I mean, what was the post? Some things that are posted are offensive whether or not you intended that and it's not unreasonable for someone to comment on that.
If it's happening to someone so often they need to physically move to a different platform, maybe they should pay more attention to what their saying and the audience you say it to.
Like if I'm with friends and someone makes a dead baby joke, I'd probably laugh, if someone recently had a miscarriage the reaction to that joke will be very different.
I wouldn't expect a lot of 4chan jokes to fly in normal society and if you can't engage with normal society without making 4chan appropriate jokes, maybe you need to work on your conversational skills.