While I sort of agree that Kabutops shouldn't be raised, it's only because it only fits one specific team type. All the reasons you stated are honestly not that relevant to Kabutop's performance, it's going to be coming in after a KO (e.g. a suicide lead) or a pivot at worst. Yeah it's frail as hell and doesn't have the best defensive typing but it's faster than Deo-S, and while priority exists it can still survive CB Scizor's bullet punch and CB Azumarill's Jet (in rain.)
CB Scizor and Azu (with a lot of prior damage,) Mach Punch users (not Infernape,) Ferrothorn, 252/252+ Mega Venusaur, and King's Shield mind games: these are really the only things that can stop Kabutops cold (as well as some mostly irrelevant stuff like Gastrodon.) Stone Miss is a bitch too.
http://replay.pokemonshowdown.com/ou-100070389 <- this is the sort of thing that happens when they don't have those things (I know dancing in front of gliscor was a little risky, and he should have sent Magnezone out after Zapdos was KOed)
http://replay.pokemonshowdown.com/ou-100105849 <- CB Scizor isn't enough anyway (I know I got a perfect chance to set up)
Those are both pretty low on the ladder (still getting my "rain team" alt up) but it's really just showing what it can do under good conditions. And really, those conditions are not that hard to meet: the things that can reliably stop Kabutops can be counted on one hand. The real issue with it is that setting up with SD depends on the opponent letting you; the number of stuff it can outright OHKO is pretty high, but knowledgeable opponents will strive to never let it get a free turn.
I still opt for C, because it really does require support and HO Rain is pretty niche. The entire team has to be dedicated in some way to that playstyle; Kabutops can in no way be stuck onto any team like a lot of the things in A and S can.