I think Fuentes is controlled opposition, and he probably overreacted a bit here, especially when he pushed her down ... BUT
... it's quite clear this woman decided to become her own paparazza. She admittedly had been taking videos of his house for several minutes before walking up to the door. She wasn't just randomly going up to the door to ask if he had a cup of sugar she could borrow for a recipe. She was effectively stalking him, violating his privacy (by taking video of his home, which could in theory capture things inside, which is where the line gets drawn), and trepassing ... going onto his property without authorization to take video to post online.
Let's say you had some other type of celebrity, say, Mel Gibson, and he saw some woman taking video of his house for some time, and then she goes up to his door (camera still rolling), and rings the doorbell. I don't think anybody would fault him for opening the door and engaging pepper spray. These people have no business there harrassing them, violating their privacy, and ... how do you know that they're not actually coming up there with evil intent? What if it's some obsessed fan, or, in the case of Fuentes, somebody who hates him for his "Anti-Semitism". Could she be armed? You just never know. If I tried doing this to some big name, whether an actor, or a politician, etc. ... I'd consider myself lucky if had gotten out of there with my life, that they hadn't blown me away, worried about my intentions.