Auctioning guardianship responsibilities seems like it will attract people or organizations who are primarily financially driven and looking to do the bare minimum, or who have to bid so low to compete that they don't have margin to do more than bare minimum. I would compare it to for-profit prisons in terms of incentives.
Just as with the foster care system, it seems like kinship is best, and next best is people who aren't doing it primarily for the money. Next best after that is arguably mission-driven nonprofits. Bottom of the barrel should be financially driven guardians.
Tbf, it's not as bad as the author's linked proposal for 'health vouchers', in which profit driven de facto health insurers have absolute discretion on whether to pay for treatment based on whether it'll be exceeded by the bonuses the government pays them for that patient continuing to be alive...
There was an article or a documentary (cant find it now for some reason) about a corrupt "professional" guardian and a judge. She would find older people or couples with some assets and no or remote relatives, come up with some bullshit story and take over guardianship in court with the help of the judge.
She'd then charge $7 / min if ward calls her for anything, would do unnecessary repairs, move them from their house into a tiny studio, and then to nursing home shortly after, etc. Basically everything she can to drain the assets as soon as possible.
What was really striking, that in some cases there were relatives who'd find out about what is going on - and even one couple's daughter could not take guardianship back from that professional guardian in court.
I don't know how widespread such abuse really is, but with the sheer amount of power that guardian has and the fact that wards are usually old, sick or disabled people, i can imagine the abuse is rampant.