Here's the funny thing that a lot of people somehow can't wrap their heads around.
Both "See-zer" and "kai-zar" are the correct pronunciations for the word Caesar.
The Legion are crazy Latin freaks who do everything the old way (Including bringing up the old issues of sixism, but that's beside the point) so they pronounce Caesar the Latin way, Kai-zar.
Everyone else, on the other hand, who couldn't care less about a dead language because it doesn't make a bit of difference to them, pronounce it See-zer.
Case closed