From what we can tell, the hoop monster in question was a part of Seattle's May Day protests. Or at the very least, he was using the day as a chance to go all Monstars on the hoop. The Seattle Police Department had a good sense of humor about it at least:
The mayor stated that he would be replacing the robot with a dinosaur back on April 16, and he asked people on Twitter to vote on which one it should be. According to Hurriyet Daily News, #7 won the poll, which appears to be an Apatosauarus/Brontosaurus(?). But for some reason they ultimately went with the T-Rex.
This story just keeps gets weirder. What’s next, a giant alien or zombie?