Tyranitar's typing, while allowing it to check lots of things, also makes it easy to be forced out. It's forced to switch out against the likes of Mega Altaria, Azumarill, Clefable, Ferrothorn, Scizor, Skarmory, Keldeo, Lopunny, Breloom, and Conkeldurr. There are things that can tank its hits like Rotom, Landorus, Chesnaught, Gliscor, and Garchomp.
Alright, well you do realize this same exact type of argument could be applied to quite a few mons in A+? Let's take Landorus-T as a hypothetical example, it's forced to switch out against the likes of Weavile, Skarmory, Chesnaught, Azumarill, Gliscor, Rotom-W, Mamoswine, etc. and also faces some competition from other bulky grounds. This is completely ignoring what it brings to the table with a ground immunity, intimidate to check physical attackers such as Zard X, momentum with U-turn, SR, as well as the potential to become an effective revenge killer with a scarf - the reasons it's in A+ to begin with. Look at Tyranitar from a teambuilding / role compression perspective and things aren't quite so cut and dry IMO. I know my example may seem irrelevant as these are two very different mons but I'm trying to illustrate a point here.
While it can take care of some of these threats with the right coverage move, it won't be able to cover them all. It's still really slow, being outsped by threats like Lopunny even with a Choice Scarf, and its lack of recovery = worn down quicker.
This is true, and one of the biggest flaws with scarftar is that it's unable to outspeed things like Torn-T, Zam, Weavile, and Lopunny that it would be able to check if its speed was a bit higher. The question is, are these flaws enough to keep it from rising? I know there is a certain amount of subjectivity when it comes to sorting the higher ranks but no Pokemon is without flaws.
Finally, you say that it is very splashable for playstyles such as sand, but keep in mind that it also faces serious competition from Hippowdon as a support / utility mon and as a sand mon, especially on balance.
I said it's splashable on ANY playstyle, not just sand. I think you're looking at this a little too linearly, look at the role compression it brings as a flying resist and a pursuit trapper to get rid of the most common hazard removers right now (Starmie, Latis.) as well as a
check to mons like Zard Y, Talonflame, Kyurem-B, Gengar, Thundurus, Bisharp, etc. Which is absolutely AMAZING to fit in a single teamslot for balance, especially on hazard stacking teams. And that's just the scarf set- other sets like a special lure to roast Skarmory, Tankchomp, Lando-T, Gliscor, Ferrothorn, and Scizor are also very effective, especially on sand teams. Chople is pretty nice too, you keep the utility of being a one time check to Gengar, Zam, Torn-T, and Zard Y while also being able to use utility moves like T-Wave and SR! As a sand setter it does face some degree of competition from Hippo, but everything else it provides is so unique that I don't think it's fair to compare them outside of that. IMO Hippo in A+ wouldn't really be
that outlandish either.
With that said, I'm not sure myself if TTar should be A+, but I don't agree with the premise of some of your arguments in your post.