It's not "there are" it's "how many"

How many before you start to get uncomfortable? Nominate your number. Then look.

edit for obvious explanation: The military links would be of more concern if these co.s were involved in military ops. They're involved in surveillance of users and data gathering. Spies and law enforcement are of particular interest. "Former cia" is widely regarded as not a thing, you can believe that or not but that very wide belief cannot be ignored when looking that just how many have found a love of silicone valley.