Actually we call them arbitrageurs and see them as helping to minimise price distortions across markets. It's only in a small number of consumer facing contexts where retailers deliberately sell goods below the price set by supply and demand that some call them scalpers.
Also landlords, even the psychotically greedy ones doing things like this article describes, are neither arbitraging nor scalping. That'd be house flippers.
The problem with the "arbitrage" argument is the scale of the arbitrage is a market maker.
When theyre constantly rent seeking you no longer have prices set by demand, rather supply set by a sustainable rate.
Thats why lawsuits against algorithmic rent setting are occiring. Part of the supply of units is being withheld by the algorithm to inflate prices and get higher ROI.
IN your pov, this is arbitrage. Real arbitrage requires an external factor no one controls.
Also landlords, even the psychotically greedy ones doing things like this article describes, are neither arbitraging nor scalping. That'd be house flippers.