The way I see it, HP is really no different than any other reviewer who engages a company to place 100s of thousands of dollars worth of equipment into their homes for multiple months if not years. He has had the very same expensive equipment in his listening room for years really no different than those he criticizes in TAS. His current site has advertisements no different than TAS or any other, just less because his site is less mature. Truth is I am not sure what his point is in his essay.
I have no issue with a reviewer, particularly if they are part of a large organization picking a "reference system" against which all other gear can be compared, assuming, they or the company they work for pay for it. When they have these "extended" loaners, by definition, there is bias inserted into the equation. Alternatively, they should have this equipment for a limited time but then they lose the capability of a "reference system" against which all else can be compared.