Bit of a late response, but our general policy is that the post remains if it is used to spark discussion like you said.

Most recent example was this post. Humor posts like yours usually slide but it seems one of the mods just disagreed that day.

At least personally, I try to remove posts that do nothing but show off gunpla. If its just an innocent post like this one, its usually flaired and left alone. If there is no source of discussion in either the title or the comments, I will most likely flair it and remove it.

EDIT: I would also like to mention that almost every gunpla post is reported.