I would be the first to agree that Trump is sometimes brash, and a little tactless, as he frequently speaks "off the cuff". However, he is frequently, FUNDAMENTALLY correct, and in this case, he does have some strong evidence to back up his claim. I happen to participate in another automotive based website, which has a very large group of members, all across the US, California included. And while some of them had their feathers ruffled by Trump's comments, many of them, the HONEST ones, agreed with what he was getting at.
It appears that the "tree huggers" and "eco-weenies" in Kalifornia have their priorities a bit skewed, and will not allow even basic brush removal and "fire gap" creation. In other words, they have created a "perfect storm" for even the slightest errant fire, to immediately feed itself, and continue on a rampage, destroying the area.
In other words, stupid is, as stupid does. Trump was just pointing that out....