You don't know Idra very well. How he responded is exactly how he reponds to everything. Same tone, same demeanor, he answers like that to every question. He doesn't switch to terran because he doesn't want to switch to the flavour of the month race that is the most overpowered at that time, they will be nerfed eventually. Might as well stick with what you're good at, and his play style suits zerg.
And yes, terran is overpowered early game. Notice how zerg have absolutely zero chance to put any sort of pressure on at the start. Terran can go 3/5 rax reaper, fast banshees, all sorts of hellion pushes. The zerg can only fight to survive past the early pressure. If the zerg makes 1 mistake (like Idra did in the final game putting down a baneling nest) then he loses. The terran make as many mistakes as he wants because his early attack can easily do enough damage with very little effort so the zerg can't pressure back. Zerg can only really pressure once they have mutas up, which take forever. One race shouldn't have a 100% chance of ending the game early in any matchup, it's just not fair to zerg that they have to fight so hard just to survive and get a chance at a midgame.