Shaggy, I reckon you will get a 50/50 response of opinions on that one.

For me, would pay to get it done if it remained in the $100's but would probably do it myself if it was north of $1000, and would used it as part of a yearly maintenance schedule.

Being young enough with a good income and a young busy family, I don't want to spend my sailing time doing a deep clean like this.

A thumbs up for your idea, but unfortunately your in the wrong state for me

Shaggy the way I'm lookin at it is from a steel boat owners veiw, forget the rigging it's gotta be replaced every 10 years anyway.
If the Result is anyway near as good as the video shows, you would have steelys lining up for touch up work , you know a little blister here and there sorta work not enough for a full sandblast. Let me offer my little ship as a sorta Guinea pig

Could this method be used on an aluminum yacht? Or it would melt away by the end of a treatment?

The fact is, l would not spend a cent more on s/s cleaning than the price of a bottle of phosphoric acid per year. Even that is an overkill.

The laborious cleaning of s/s wires is not my kind of fun.
The life lines were covered by 1/2 inch conduits and my eyes are too bad to see the rigging up there. Besides, thanks to our insurers, the standing rigging is condemned after ten years regardless of it's condition so why bother?? They never leaked rusty crap on deck.