We have had an unequivocal apology, made on national television by the Prime Minister himself, saying that the conviction was "horrifying" and "utterly unfair". I think that counts as "an acknowledgement that the laws of the time were injust".
A pardon is a separate and distinct legal action, which is unwarranted.
It is a whitewash. The treatment of the homosexual community at that time was horrendous. Pardoning his act because it's non-objectional today is stupid. Why not pardon all the Jews of the pogroms for having the wrong ethnicity.
It's whitewashing because the act of doing it is more offensive than simply leaving it as is. Pardoning Turing would be pardoning him for being gay and makes no correction for the horrendous treatment he received, which was the point of the apology.
An apology is what Turing deserved. A pardon is an insult to his memory.
I'm sorry, but you simply don't understand the meaning of the word "whitewash" http://www.merriam-webster.com/dictionary/whitewash. You don't "whitewash" something by publicly apologizing for it or by pardoning someone who has been wronged. That's almost exactly the opposite of what the word "whitewash" actually means. When you "whitewash" something you DENY that it happened or try and BURY it.
A pardon is a separate and distinct legal action, which is unwarranted.