Yes, but an explicit apology forces a benchmark of accountability: if the government apologized to group A for committing B, why are they still committing B to group C?
"forces"? You clearly don't have much experience with groups of monkeys.
Some of the known-successful ways to get around said "benchmark" are "this time it's different", "this government is good", "group C deserves it", and "we're not doing B".
I personally think its unlikely that an apology to Turing will change many attitudes to homosexuality or encourage a (lasting) crack down on discrimination.
What countries require homosexuals to be treated with mind altering drugs? Iran actually goes beyond chemical castration with required physical sex changes: it is illegal to be gay, but it is legal to be transexual. http://en.wikipedia.org/wiki/LGBT_rights_in_Iran
