Both games look outstanding, and though your comment was hyperbolic OP, I see nothing wrong with it considering pretty much everyone here unfortunately speaks in hyperbole. I honestly can't stand hyperbole in general, but if we're gonna allow people to trash pretty much any Xbox first party games with terms like shovelware and mediocre when their metacritics are in the 80's, then I can't see how there was anything wrong with your comment in terms of relativity.
Again, I love Gran Turismo and Forza, no dog in this race and to be completely honest I prefer the analytical look of Gran Turismo to the "louder" style of Forza, but I don't see why you were banned or why your comment was seen as so problematic in comparison to many of the posts I see here. The level to which people trash Xbox daily on this forum far exceeds that, and I very rarely ever see those posts actioned, though it does happen.