All of that is subjective. Every single person will have a different interpretation and clearly the colleagues were fine with it. Without knowing what was actually said, there's no objective measure of whether anything even crosses the professional line or if it was this person just finding it personally disagreeable (which seems likely given the rest of the note).

There needs to be some pushback on how far people expect others to constantly read their mind and cater to their level of offense and sensitivity. Otherwise workplaces and society itself will start to grind to a halt.