I think you're misunderstanding me. I'm not saying Gliscor is a bad Landorus T. I'm saying Landorus-T fits more offensively than Gliscor. Even as I said, Gliscor is an excellent Stallbreaker, and while I forgot about Sub-toxic it's still a role Gliscor can fill efficiently.Oh my god, Landorus doesn't outclass Gliscor, they're entirely different mons with different jobs that just happen to have the same typing. Gliscor is a more than viable stallbreaker, but can work more defensively with a sub-toxic or specially defensive role. It's even used as a stat receiver on certain Baton Pass teams.
The only similar (ish) sets are the defensive pivots but even they do different things, Landorus' role generally is to get chip damage on stuff throughout the game while keeping rocks up, generally on more offensive teams. While Gliscor'a there for longevity based reasons thanks to PH and Roost.
I'm not fussed where Gliscor goes, I think it's good enough for A- still, but not necessarily that much better than B+ Just stop saying it's a bad Landorus-T
However, I do think Landorus is more of an offensive mon, whereas Gliscor is a more defensive mon.