From the very beginning it becomes clear that Hubie is often a target of ridicule. Whether he's getting made fun of at work or chased down by local troublemakers while riding his bike, there's no shortage of characters taking their mockery way too far.
Yes, it's instantly clear that Hubie is different. He even talks with a lisp à la Carl Spackler from Caddyshack, but that obviously doesn't give others the licence to make fun of him. It may be worth reminding your kiddos in a larger conversation that it's never kind to tease people just because they do things differently than you.