Note that they didn't exert any control. It was discussed between colleagues. The email chain contained many warnings not to do this. Ultimately nothing came of it.
No. Why would it be? At an absolute minimum conspiracy requires some agreement. Which they didn't have here. This also seems to have been an open discussion so there was no secrecy amongst those who did agree.
IANAL, according to Section 1(1) in [1] for UK, the threshold is for two persons to agree to have the law applied to them. It doesn't require all to agree. And from 1(1)(b), it's not necessarily for the conspired act to be carried out under some circumstance.
For U.S. [2], the threshold for conspiracy against the U.S. government is similar or lower. Item (2) "they interfere or obstruct legitimate Government activity" sounds a lot like what the Google employees were doing.