In an Iterated Prison's Dilemma, Tit-for-Tat and Win-Stay-Lose-Change are both viable winning strategies from a game theory point of view. If your competitor is playing one of those strategies, and you aren't, then not responding to an attack merely guarantees continued loses.
In plain English, you are willing to forgive Google their transgressions because you feel that they are being attacked and you like/work for them, but not Apple/Microsoft for spurious reasons; this being the cognitive dissonance I alluded to earlier. When it is pointed out that this is not the actual case, you claim that that they are in fact being attacked and it's not fair, so they have to resort to the same tactics, which is forgivable because you like/work for Google. Google are as bad as Apple and/or Microsoft.
