not sure how far you or anyone else has read so this may be SPOILERS******
Not gonna lie, Xavier did come off as suspicious initially, but I have reason to believe he's a good guy and I also have a small theory as to why I think so, referring the points you made:
1. Lance most probably thinks pristine carriers are "pampered" for the "work" that they "do". I'm sure you get what i mean.
Lance had a tough upbringing as we all know, at that time a thought that would be going through any child/young teenager's mind is how nice it is for the people in Resoom. Although he is much wiser than at that age, he still thinks that the carriers are being treated and pampered like eggs despite actually knowing what's happening to them. Why he keeps selling them is easy, as after being literally kicked off the team he has nothing and is unable to provide for himself. And I don't think putting 'former raider' on your resume is going to get you a good job, since it's all he knew how to do at the time. So being presented with an opportunity to pay some bills must have been an offer he couldn't refuse. As to why he sold Xavier is a personal theory of mine and I'm sure other people have come to this conclusion too maybe idk. So it was hinted briefly that Lance and Aaron were a thing ; ) , but they fell off somewhere. It's clear that the space in Aaron's heart was quickly filled by Xavier, leaving poor Lance with an even more broken heart that may have been revived by hatred and spite, Leading to the decision of selling Xavier becoming very easy. Other than thinking that they are pampered I think Lance has no reservations or hateful feelings toward carriers
2. Well, he does know of the existence of the carriers and considering the breakouts that have been occurring and how I said he thinks about the carriers, it shouldn't really be a surprise anyway. um, as everything else you said, the thing about supervillains is: They no matter what think that what they think or their way of thinking is correct so considering the antagonistic role he's been playing we can assume this is evident( but I'm sure all he needs it some talk-no-jutsu, fix him up rq ;) )
3. Don't forget about the amount of time each had spent in Resoom. If memory serves me, Xavier was there for 50-100+ years while Cyrus was there for 300+ years so it's obvious that Xavier was less sluggish than Cyrus was, but HE STILL WAS HEAVILY AFFECTED as his sluggishness is what lead to the death of his rescuer.
i would have reached a similar conclusion that Lance is a money hungry backstabber, but the bond he formed with Cyrus just proves that he only wanted some love and attention like any other puppy would : )) . hope this clears some stuff.