It's the team more than the rider. I actually really like Del Toro and the way he rides, and if he left UAE I would cheer for him, but the team deserve as little as possible and every time they lose a race it feels like a small victory. It is also then funny to make fun of them.
Del Toro made a silly mistake, it was obviously nothing more than that, and the overreaction was almost all tongue in cheek (I think). However it should also needs to be said that this was also an amateurish fall from Del Toro which I am sure his teammates and other friends in the peloton will make fun of him for, so I don't think calling him a clown etc is overblown.
It's sort of the equivalent of a footballer tripping up over themselves and then going head first to take someone out – it is genuinely quite clownish and slapstick to clip your inside pedal on the ground going uphill, spin round, and take someone else out with your arm.