The son of the Florida grandmother who lost her arm in a savage alligator attack claimed the beasts are getting bolder around humans — because of nitwit tourists and attention-hungry TikTokkers that feed and pet them along the river. Zach Guerrina — whose mother Dina Spann, 58, became the gator’s midday snack Saturday as she floated in Silver River in Marion County — said he’s swam in the river “hundreds of times” and not once has ever encountered the cold-blooded reptile. “Growing up in Florida, that has never been a thing. I’m in the water all the time and I’ve…