It can be quite exhausting. Typically, one instructor handles a group of four or five people for snorkeling, but I opted to pay extra to have additional staff on the boat dedicated to looking after my son. The locals are usually more adept at swimming. Unfortunately, there are no direct flights from the mainland. You can, however, connect through Singapore or Kuala Lumpur. I’ve heard that there’s only one weekly flight from Singapore to Komodo. Generally, you’d need to make a stopover in Bali.
The Komodo adventure sounds amazing but exhausting. Having extra staff for your son was a smart move, and it’s good to know the locals are strong swimmers. The travel logistics sound complicated though—hopefully more direct flights will be available soon.