If he's referring to the original TSRP, I don't have an opinion since I've never played it.
TSRPR, though, is hard, but certainly not extreme.
I'd still argue that Super Mario Infinity is very hard
because its design is flawed. True, a hack can be very difficult due to unforgiving, but clever design, but it can also be tough for artificial reasons or flawed design. In either case, a no-tools player can be in for a miserable time. And seeing the main criterion for being given the Very Hard classification is a need for save state spam, I think the Infinity games definitely meet that requirement.