The "porn" filters are stupid and creeping totalitarianism, but it's irresponsible and disrespectful to compare them to what was done to Turing.
He was persecuted and prosecuted; publically humiliated; forced to receive hormonal injections that rendered him impotent; banned from traveling to the USA; essentially banned from any jobs involving cryptography or national security; and ultimately committed suicide in large part because of government sanctions.
World of difference between that and a porous filter.
He was persecuted for his sexual orientation, and furthermore this was done despite his obvious contribution to the safety of the nation. This placed sexual mores as more important than national interest.
A default information filter is currently being introduced by several ISPs in the UK, it starts by filtering sexual content.
This is similar in concept to the attitudes that cause immense suffering to Turing, i.e. controlling the public expression and liberty of the sexual life is being considered as more important that protecting civil liberties such as freedom of information.
>forced to receive hormonal injections that rendered him impotent //
He wasn't forced to receive hormone injections he chose it in preference to serving a one year imprisonment. As an expert chemist he was no doubt aware of the implications of that choice.
My reading of this has always been that his apparent predilection for picking up teenagers made him a massive security risk. Surely had he done the same with teenage girls he too would have been banned from jobs involving high level security clearance. It also strikes me that maybe Turing didn't like that element of his life?
[I have a pop-psych theory on this all being related to a fixation on Morcom, his childhood friend who died. But 40-something men lusting for teenagers is common enough that the theory lacks support.]
The best pardon to someone who is dead would be to stop doing similar misdeeds to those who are living.