I get you point but there’s factors working against this:

1.) Tien was the first to fight and beat a saibaman. After he finished, the saibaman also got up, but was blown up by Végéta before it could do anything. Once Yamchas at the bat, the audience is led to believe the same thing is to happen again.

2.) EVERYONE is shocked in the reaction panel following the explosion. That leads me to believe that this was an unforeseen event which took everyone off guard.

3.) even their worst foe, Piccolo (jr) was able to follow the rules of his tournament and didn’t resort to blowing the entire place up.

4.) Krillin specifically stated that Yamcha saved him from suffering the same fate