One of the things that is so interesting and ironic about Gurathin is that he's a suspicious dick, but he's a suspicious dick who is actually right a lot of the time - he's just so spectacularly wrong that ditching SecUnit will give them better odds of survival.
He was suspicious Murderbot would listen in on them if they weren't in the Hopper...and he was right! It DID do that during all their other conversations!
He was suspicious that something was seriously off about Murderbot's programming...and something IS seriously off about Murderbot's programming! (It's just that, you know, that's a GOOD thing - both ethically and, very directly in the book, for PresAux's survival)
He was suspicious Murderbot would kill them....and though book Murderbot would Never, show Murderbot seems to have actually considered killing them, if briefly
He was suspicious that Murderbot might kill them, the people it's supposed to protect....and Murderbot HAS killed a bunch of people it was supposed to protect
He was the only human on the team who refused to give Leebeebee information (presumably at least in part because he is suspicious of outsiders in general, and at least in part because he knew Leebeebee was from the Corporation Rim, though yeah that was also probably just him being a dick also). And as we learn, HE WAS RIGHT NOT TO DO IT
He suspects that someone is trying to kill them the minute something goes wrong...and someone is, in fact, trying to kill them! like, as we know from the books, the reason they didn't know about the giant predator worms WAS because someone was trying to kill them
He suspects the corporation is spying on them....and the corporation HAS installed spycams everywhere! And in the books, this is for the express purpose of data mining! (maybe in the show, too? I'd need to rewatch the episode)
He and Murderbot are the only ones in the PresAux camp who have any concept of opsec (in the show). this is part of why they hate each other
Really, Gurathin's suspicious nature would be actually very useful..........if only it wasn't pointed so thoroughly in the wrong direction