Prison did in fact convince Hitler that armed rebellion was not an effective means to seizing power in post-WWI Germany. He had been jailed for the "Beer Hall Putsch" in Munich, which had in turn been inspired by Mussolini's successful "March on Rome".

After his release he decided to focus instead on gaining power through the political system, an effort that was ultimately successful.

So prison "tamed" him in that sense, but of course it did nothing to reduce his political ambitions. If anything the opposite appears to be true - he wrote "Mein Kampf" in prison, which laid out his vision for what the German state should look like, including such details as gaining "lebensraum" - more living space for the Germans in the East.