One major thing that you may have missed, 1) Zoat mentioned that there would be far more of them and they would be more varied and 2) Paul is actually going to check things out with the various group and faction within the Controller before deciding anything.
Zoat's an unreliable narrator.
If you actually look at Paul's actions, you notice him setting his ring to automatically go to the "senior Controller on Maltus" upon his death, which only makes sense if he has already 100% convinced himself that the Controllers are a force for good. (It bears noting that the Controller I referenced, who wants to wipe out all life in the universe in the name of Order, was at one point the
only Controller on Maltus in canon--though I have no idea whether he even exists in this universe, of course, but then, I wouldn't think Paul would know either.)
His explanation for that was because "Sending the original ring to Maltus discharges my responsibility to the Controllers", which makes sense on the same sanity level as Grayven's tales of his childhood on Apokalips, given the lack of any prior contact in reality with the Controllers.
... which, I realize as I'm typing this, makes the implicit assumption that Paul's story about the Controllers having been in charge of an OLC at one point and his ring having originally come from them is obviously a lie that he made up to make it seem as though he had powerful backing behind him. The contrary seems obviously nonsensical to me, but I guess if someone wants to argue that, Paul might be saner than I think.
Do the Controllers/Guardians/Zamarans know about the White Light of Life? And if so has any experiments every been conducted with it? Or the Black Light of Death.
The last pre-New 52 GL storyline showed the ancient Maltusians of Krona's era (which was right before the Guardian/Controller split) having "Life" as their focus rather than a particular emotion, and wearing the White Lantern symbol, so presumably?
Might not be true here, of course.
Counterpoint: Larfleeze's rings had to come from somewhere.
When Larfleeze found the OCPB, he channeled directly from it, with no rings in evidence, so presumably they came later. In fact, rings hadn't been developed at the time he found the OCPB (at least in normal canon), so they would have to have come later.
The Guardians do send rings to recruit GLC members from the Vega System, even if they can't serve there. Larfleeze has the ability to scan outside Okaara, and seems able to sense incoming ring-wielders, so he should at least be
aware of the existence of GLC rings.
My guess would be that either he just grabbed and assimilated a GLC ring, or he scanned one,
wanted an Orange version, and the OCPB obliged. Given that he could channel enough Orange light straight from the battery to kill a Guardian, it doesn't seem implausible to me that he could channel enough for either of those scenarios. (I would also assume that channeling directly from the OCPB has deleterious effects on your sanity, but, well, Larfleeze.)