I think your unfounded suspicions amount to FUD - Fear, Uncertainty and Doubt. You have no evidence that people concerned about climate change would be more underhanded or less loyal to their employer than other employees. A company has no reason to fear working with another company because its employees exercise the right to free speech.(+) Claiming such a fear is rational... Well, I think you can see how that would cause people to shut up because they are afraid of being seen as a liability and fired. That would be bad, wouldn't it?

A similar situation existed in many Western countries during the Cold war. Communists were afraid to speak their mind because they would be labelled Russian spies and they would be blacklisted. There were of course lots of people that spied for the Soviet union though. But crucially, only one (that I know of) were a devout Communist. All the others were spying for monetary reasons.

+ - Last I heard an American senator recently proposed that the US should stop selling crowd-control equipment to China. If a politician can propose that, why can't an employee propose that Amazon should not host oil exploration companies?