Stamkos should play
First off, don't worry about Stamkos protecting himself. There are more fights in an average OHL game than at this prospects tournament and Stamkos has figured out how to thrive in the OHL. In fact, Stamkos has been a marked man for years now as his reputation has grown, but he's managed to stay healthy despite the potential cheap shots and challenges from fighters.
If the Lightning wanted to make sure Stamkos attended their main camp, then why not the same concern for the other prospects? If the team is sending prospects, then send prospects. Don't separate Stamkos and mark him as special.
The prospects tournament is a clean, hard hitting series of games. I understand not letting Stamkos take any risks that might sideline him for the NHL ... but only for non-hockey risks. Don't let the guy ride a motorcycle without a helmet. Heck, don't let him buy a motorcycle. But this is playing hockey. And playing hockey against pros is something that Stamkos needs to continue his development. Playing hockey isn't risky for Stamkos, he's an expert. So don't baby him.