This one is easy: PGC is the "good guys" and Streel is the "bad guys". 

One of the big theories that was floating around the early days of the internet (circa Y2K when geocities was the big personal webpage hosting site and discussion boards were in their early "treebranch" formats) was that PGC was responsible for usurping Streel's efforts on Volturnus.

What supports this theory? For starters, back when the Volturnus trilogy was penned there was no such thing as Streel as that name didn't appear until the KH expansion set debuted a year later (its first use in an AD setting didn't happen until SF:4 Mission to Alcazzar, again printed after the KH set)...instead it was merely a Truane's Star expedition and the "friendly Truane's Star battle fleet" that saved the day at the end of the trilogy.

KH states that Pale's militia consists of a frigate and three assault scouts. No sane government is going to dispatch its entire defense fleet and leave themselves vulnerable to attack just to investigate the happenings in a remote unexplored world as a result of a second expedition team sending out an SOS. It just doesn't happen. Not to mention that force probably isn't enough to contend with whatever fleet the Sathar sent to Volturnus --- IIRC SF2 quotes 40K ground troops (not counting vehicles, equipment, and cyber-beasts) which, according to KH, would mandate no less than 40 assault transports that can ferry 800-1000 troops each and "carry very few weapons, relying heavily on other ships for protection." One can only theorize as to what the rest of the fleet would look like, my proposed fleet can be seen here: SF:2KH Liberation of Volturnus. Note how my proposal in Game #2 includes only the frigate from Pale's militia (along with two gunned escorts, not assault scouts...those three stayed home to protect and inspect).

Anyways, the bullet point here is that as written, the Volturnus expedition is a "Truane's Star government expedition". Since we know that any "TS government" would actually be based on Pale and New Pale (since both are listed as populated worlds in the original rules), we can presume that the local government would be backing the operation more than conducting it, meaning it is a joint venture. Who best to join forces with other than the local home office mega-corp on Pale? Yes, that's Streel if you need to look it up (also note I included more Streel ships in the Liberation scenario than any other sanctioned group, since a successful business is run better than a government it stands to reason they'll go out of their way to protect their investment).

Which leads to the next question: who would be most interested in foiling an operation involving Streel? Pirates? Maybe, but for the most part they tend to operate alone rather than as a huge group with a common cause. A bunch of pirates operating as privateers? Okay, that is starting to make more sense. But who would they be operating under? None other than Streel's biggest competitor, the rivalry that is mentioned in more canon and non-canon SF material alike than any & all other mega-corp operations combined: PGC vs Streel.

So it has to be PGC pulling the Star Devils' strings, and aligning themselves with pirates to hunt down & kill scientific exploration teams is anything but what a bunch of "good guys" would do...alas since the pirates escaped we'll never know for sure. It makes for a great conspiracy though, and most folks certainly wouldn't put it past any big business to behave in such a shady manner in order to usurp their competitors.

Guilty or not, it behooves PGC to make themselves out to be the "good guys", more so if there is any hint of  credibility behind this conspiracy...and believe me the hints are a-plenty.