If so that's fascinatingly clever.
If they are, it is. Although as demonstrated on this thread, when one person holds a belief they know to be "true" (whether that's in gender identity, ghosts, astrology or whatever) it can create a whole different conversation when they hear something that they perceive to be dismissive about their belief. Including whether the belief is a belief or a fact (that not everyone knows/understands).
This is a microcosm of the problem that has been happening with gender identity. As an analogy, if UK Christians within parliament successfully passed a law that everyone needs to go to church on Sundays, they would get pushback from the public. Some Christians would oppose it, some might welcome it (they might talk about how beneficial it is for everyone to take time out and be a community etc.... Be Kind). Some atheists might welcome it on the same basis. The opposition from atheists would be a mix of a) people saying it's wrong to impose this on everyone, because not everyone believes in god and b) people getting angry at the overreach and saying that god doesn't exist. That's what's happening here with the "playing make-believe" comment.
The question is, will the reaction to the "playing make-believe" comment be a loud conversation that overshadows the real issue, so that people spend time arguing about whether it was kind or offernsive? There will always be people who believe that we all have a gender identity, just like any of the other beliefs above.
Edited for clarity.
Ps everyone is welcome to tell me that ghosts aren't real.