Can we all just remember this an extremely weakened AM we're putting him on tiers with and he still scales lower than him. The tendrils thing I kind of call issues with that. When AFO used the tendrils period they didn't seem to pierce anyone in the Kamino fight(Kurogiri is the most obvious example) so I really don't take that as an issue against Endeavor, AFO even said he wasn't seriously fighting AM until everyone left he was just trying to wear him down. Here he clearly was attacking people with intent to Kill/harm in the case of Deku. Also Gran torino is a weird case because gran torino has had showing of taking punches from AM before too so the fact he survives a punc from shigaraki also isn't an effective counterstatement considering the series frequently has him in fights with the top tiers of the verse(I really don't believe his High 8-C rating for a second). There are many cases of Normal human characters reaching higher power levels, (Mirio onshotting Kirishima, Endeavor being able to somewhat contend with Hood physically, Gran torino's physical strength and durability). I understand people's issues with Endeavor's scaling but A there's really nowhere else we can put endeavor him being 8-A would be so inconsistent it would be laughable, and B he still scales below a weakened AM's durability as he would be baseline Low 7-B+ in the new scaling chart.
Also, the idea of Shigaraki holding back at that point is laughable, he was clearly fully in the fight at that point and was excited, and makes no sense for him to hold back in the fight at that point, he was also clearly serious at that point judging from his clearly pissed off face before he punches them.