I hear what you’re saying but it’s standard procedure for the FBI to get involved in any suspected eco-terrorist act. This has been going on in WA, OR, CA, CO and other states for 15 or so years.
Back when I was a COTR (contracting officer's technical representative) and DoD employee we had strict guidelines. Obviously, we couldn't play favorites when evaluating contract proposals. But going further, we had to studiously avoid even the appearance of impropriety. Government ownership in GM makes that just about impossible in cases like this, even if we trust that this is an entirely normal investigation.