Argus are from indo, yellow-chinned monitors are from OZ. Different subspecies.
Also, not that it even matters, but Argus, V.p.horni and V.p.panoptes, both occur mostly around water, they swim(seen it) they hunt(seen it) and patrol(seen it) these areas.
Argus and its Ozzie brothers, also at times occur in wet and dry grasslands, in the case of dry grasslands, usually not far from water. Maybe reading about them would help. But fortunately, I have seen lots and lots of these.
About keeping them together, I have not had problems, if fact, I have seen more problems with conspecifics then different species. Also, at one time, zoos had this multispecies enclosure thing going. They would commonly keep different species together.
I have kept many different species with other species, from adults, to babies, etc. In fact, I have this little experiment going now. Ask Rsg, he has seen it. I am keeping a young adult female gouldi cross in with a pair of mertens. Not only do they not fight, the cross somehow has decided its a mertens. She swims with them, hangs out with them, feeds with them and generally acts just like the female mertens. She has cycled and laid infertile eggs a couple of times. There was some sexual activity, but no breeding as been seen.
Now to explain real experience. I have seen and would expect, the same type of behavior and the same infertility when introducing a new female mertens to the enclosure.
One of the reasons I even put them together, I lost(murdered) the male cross, she was bonded and produced successfully with. Since then she has been with three other cross males and has not produced good eggs since she lost her mate.
Also, for grins and giggles, I once put an adult male lacie with a large adult male argus. Funny thing is, the lacie treated the argus just like any male lacie. He chased, tried to fight, and otherwise bullied the argus. But after a month, they became good buddies and got along fine, and even would gently take food from eachothers mouths. Yes, I realize this is not nature and in nature the results may be entirely different. But thats exactly the point I hope you get out of this.
You know I could go on and on. I could include pics of the lacie and perenty. Or even ackies with tristis, or storrs but what would it matter?
The truth is, you have either no experience or have not done a good job at introducing monitors. Either way. Or the real deal is, its all a figment of your imagination. You simply made it up. (very common on forums)
By the way, years ago, this young fella use to hang out here and he raised a male Sav with a female argus. The dang things bred and produced several clutches of good eggs. Some of the eggs hatched. Many went full term. Funny but pics of those looked exactly like argus. And please do not give me the eggs didn't hatch because they were hybrids. The fella that had them, had never hatched an egg before. Therefore, he did a better job then many here who have killed many many "pure" eggs.
Again for real truth, there is no more danger in keeping two similiar size species together, then two individuals of the same species. The rules are the same, the younger they are the better. Oh, and make sure they are not starving, that starving thing ruins even the best pairs. F