Two schools of thought...
1. He has flatted a shove after your raise, and more often that not that"s a sign of weakness and an opportunity for you to exploit with a shove to isolate and reach showdown with the shortstack with dead money in the pot.
2. If you flat behind, with a dry side pot, it"s much easier to play the hand post flop as bluffs from him are unlikely.
From my perspective, early doors in the tourney, with weak/marginal hands, I call for value knowing post flop play will usually be straightforward. With strong hands AQs+, TT+, I re-raise... and we"ve already seen him call against strength, so have to assume he has something he wants to see a flop with, so I think we can re-raise large enough that we theoretically commit stacks.