If the Dominion could start a supernova with trilithium and whatnot, I don't see how it would be beyond Trelane's abilities.
You could say the same about any character who gained access to the necessary technology. I don't see the connection to Trelane specifically. Why even bring up supernovae and Trelane in the same thought? It's a very confusing non sequitur. Are you referencing something from the comic?