This symbolism seems like a message, but for whom? It might be for his supporters to say I'm still in charge. However, for all we care, he could be riding around in monster truck. Actually, that would be pretty cool. It's not for the general public because I doubt the media is going to show them anything that even remotely contradicts their narrative, no matter how benign. This fits best into the narrative that many of the dirty deep state operatives already know Trump holds all the cards and that he's holding off on wiping them out to make them squirm. This might just be another small detail to keep making the sweat.