Colorado - What Can Be Asked So Terminally Infirm People Stop Getting Abandoned At An Apartment Complex?

Location: Colorado. I posted this in the landlord subreddit, but my landlord likely needs genuine legal advice. He's 78 and not getting online anytime soon. He has a fourplex and lives in one of the units

People keep abandoning family members in his fourplex to die. It's been two elderly people now and a younger guy with severe mental health issues. Generally they are the ones who are signing for the unit, but they're guaranteed by a family member who turns out to have legal conservatorship or PoA for them and didn't exercise it in their best interests. It takes at most a month for it to become apparently the tenant in question needed to be in an assisted living situation; none of them have made it more than six months.

I've called APS a few times, but we're hella rural and they never make it out in time. It turns into one of us repeatedly calling EMS, and the hospital ultimately returning them here alone because this is where they live. The cycle repeats until one day we can't dial 911 fast enough.

We're both getting traumatized by it. Plus it tends to tie up the unit for months between tenants, because everything becomes abandoned property, subject to probate, or a crime scene. This is the landlord's income, so it affects him pretty significantly when one unit goes unpaid.

What can legally be asked during screening to prevent this from happening? I presume tenants can't be screened just because they're elderly and a landlord can't ask about health concerns. He's not even sure if he can reject someone under conservatorship if their conservator agrees with the arrangement. It's very difficult to rent without a guarantor in this area, because everyone is either retired or in some form of seasonal contract work (he's tried and the only taker he got was me). putting them on month to month and declining to renew isn't a great strategy, since often anyone that can help the tenant be mobile disappears and screens his calls (both elderly folks mysteriously had their DLs suspended and their cars confiscated by family with 48hrs of moving in). He's at a loss.