They could also write the comment in French, and by the same argument people should need to go out of their way to copy-paste that into google translate.

Thousands of people are going to read this thing. The writer could spare thousands of people spending tens of seconds (totaling days of human life), by simply spending less than a second spelling out the obscure term.

Boy are you going to be surprised when you find out that there is an entire French literary tradition that doesn't concern itself with who does and does not speak the language.

Who's going all the way to Google translate to copy and paste? You just select the text and right click/long press and select translate.