I can see that on the scale on individuals? But governments? They make a habit of going against what the previous incumbents did or said, just so they look like they are doing something different.
As such I don't see how this apology will make one jot of difference to the UK governments future actions (it already has openly gay MPs, I can't see them backing legislation that criminalizes their sexual preference).
There is a legal fiction that a government is not merely the vector-sum of actions made by its functionaries, but that it has a corporate identity that decides and acts and persists over time. This is fiction, of course, but it's a useful fiction--a model, if you prefer--and it has some connection with the way humans as social animals identify with their tribes.
So the United Kingdom (represented by its Home Office and judiciary in the 1950s), as a thing with a corporate identity, did wrong to Alan Turing, and it is appropriate for the United Kingom (represented by its Prime Minister) to apologize for its misdeeds.
It's more of a way for a society to formally make reparations for past bad (group) actions. Even if the person is dead, there is an implicit promise to never let this happen again.
As such I don't see how this apology will make one jot of difference to the UK governments future actions (it already has openly gay MPs, I can't see them backing legislation that criminalizes their sexual preference).