Sorry but this comment is either grossly imprecise and dictated by hurry
in writing up[, or it underlines a gross misunderstanding of the GPL. In
either case, as it is just false.
First, a copyleft license by nature,
Being GPL compatible is not difficult at all, in most cases modern
licenses that are not GPL (at least v3) compatible, are not by choice,
so you should really look at both sides of the equation, you cannot
blame the GPL for lack of compatibility, compatibility is always a two
sides story.