It's great that people are taking a moral position re their work, and are seemingly prepared to take a bit of a risk in expressing themselves.
However, if we're honest, Google has a long history of selling 'the people' out on domestic surveillance. There is even a good argument that this is what it was created for in the first place, given it was seeded with money from inqtel, the CIA venture capital fund. So, while I commend acting with your conscience in this (rather minor) case, and I'm glad to see people attempt to draw a line somewhere, what will this really come to? I strongly suspect this is event itself is just theater for the masses, where corporates and their employees get to stand up to government (yay!). The reality is probably all that is being complained about, and far worse, has been going on for years.
How far would these signatories go? Would they be prepared to walk away from all that money? Will they stop the rest of the dystopian coding/legislation writing, or is that stuff still ok (not that evil)?
Ultimately, is gaining the money worth the loss of one's soul? If you know better, and know that it is wrong to assist corporations and governments in cleaving people open for profit and control, but do it anyway for the house, private schools, holidays, Ferrari, only taking a stand in these performative, semi-sanctioned events - is this really the standard you accept for yourself? If so, then no problem. If not, what exactly are you doing the rest of the time? Are you able to switch your morality/heart/soul off? Judge yourself. If you find you are not acting in accord with yourself, everything is already lost.