It's not like he can really keep his guard up around a man that can conjure alcohol from nothing, so he might as well enjoy himself and if it all turns out to be a trap for heretics or whatever he's dead either way.
"Well, when I got reassigned to the central organization, with the 6th circle wizard in charge, I mostly didn't get to know about what was going on. But before that, when I was with a smaller group, we pulled some clever schemes. No big dastardly Asmodean plots, just the typical grinding turn of the hierarchy and bureaucracy that we jammed up when we could. Like this one little village, it had previously had a rotating priest, you know, on a circuit, and they were planning on expanding with a regular permanent priest and a little village temple. We couldn't risk revealing ourselves, or even make them think to look for humans, so we came up with elaborate ideas to convince the Asmodeans that the area had an undead problem. The wizard pulled some clever tricks to sell them on the idea. Like he had some clever spell uses to make it look like a corpse had tried to claw it's way up out of the earth, and he faked ghostly residue with egg whites and a prestidigitation, a few other tricks like that."
He will elide the tricks that were more like desecrating dead bodies to try to get some actual undead to arise. There's enjoying himself talking and then there is being an idiot.
"I was mostly just dumb muscle, helped kill the first group of weak adventurers that was sent to investigate. We ditched the area after that, we figured they would waste a lot of effort trying to put down undead that weren't there."
Because their corpse desecration didn't actually result in any real undead.
"We might have only killed a few of them and wasted some anti-undead adventurers' time and delayed the new temple by a few months, but still I figure a few months without some Chosen lording it over the people are a few months that were better, right?"
Mateo smiles amicably at that concluding thought. He thinks he's figured how to reframe things as 'Good' pretty well.