When Kuroro was captured, Nobunaga told the other Spiders to not pursue Kurapika because Kurapika has another 'pro Hunter level' friend. There were 5 Spiders at that time.
And even though Pro Hunter originally is a rather lofty standard, there's no way Kite is below the average "Pro Hunter" even in this regard.
Again a Pro Hunter is someone that if you got 2 of them (Kurapika + one other) it's enough to make 5 Spiders back off. The original "Pro Hunter" level is easily more than a match for the average Spider. That's why Hunters hunt the Spiders, not the other way around, even though Hunters clearly operate in much smaller numbers as a group compared to Spiders.
Ants have unbelieveable aura reserves but that's more of a capacity, not output issue. They'd be able to fight 10 times longer than any human can easily but their maximum output at any given time is surely not 10 times that of the strongest human, or there would be utterly undefeatable. This is also why the fact Pitou might be wounded against Kite is fairly irrelevent, because the Ants certainly can withstand at least 10 times the damage compared to the strongest human (random grunts can tank Ko level hits without aura just as a function of body strength) so Pitou would have no reason to worry about getting at most flesh wounds. It's just like Kurapika doesn't care about injuries becuase he can heal himself with an ability.
Finally Ubogin is not stupid. He assumes Kurapika is an equal level user and he's either Manipulation or Materialization due to chains. Let's look at a Materializatino user from Spiders: Shizuku. She lost to Gon in arm wrestling even though she used aura while Gon did not (the scene shows one of the two using it, and since Gon has no idea how strong his opponent was there's no reason he'd start out using aura on a seemingly fragile girl). We also see that later Nobunaga easily beat Gon in strength under normal circumstances he's not even at the halfway mark in physical strength amongst Spiders. Likewise Shalunark, a Manipulation user, is ranked roughly the same in physical strength as Shizuku. This means Ubogin is unfathomably stronger than an equal tier Manipulation or Materialization user and this is supoprted by his own friends. Even 20% of his maximum output should've been enough to break the arm of a Manipulation or Materialization user and then you don't have to worry about what trick they got on their sleeves. Kurapika talks about his superior strategy but what ultimately worked was his Emperor Time allowed him to tank hits from Ubogin as if he's Reinforcement. This made Ubogin switch from his anti-Manipulation/anti-Materialization user strategy because his experience says only Reinforcement users can tank his hits.
Another way to think about it this. Suppose Gon at GI is same level as Hisoka (he's not, but this only makes it more favorable for the comparison), we know Gon's strength is roughly equal to Razor's strength with aura beasts out. Therefore, Razor's attack are at least equivalent of a Reinforcement user equal to Hisoka's level, though in reality the difference between a Reinforcement of Hisoka's level to Hisoka should be even greater (because Gon really isn't the same level as Hisoka to begin with). Well we see that Hisoka absolutely cannot tank Razor's reinforcement attacks (throwing the ball is pure reinforcement). He always used a special ability to lessen the impact, and even Razor's small aura beasts is strong enough to break his fingers with the impact of their strength alone. Likewise Kastro, a Reinforcement user, has no problem ripping Hisoka's arm off, and no I don't think Hisoka purposely lowered his defenses to lose his arm just for fun. It's pretty clear Kastro does have the strength to do this rather easily (though Hisoka certainly could do a better job dodging).
It's pretty well established that you don't tank an equal level Reinforcement's direct attacks unless you're also Reinforcement, because if you tried to tank it you'd be lucky if you only lose a limb. That's also why Reinforcement are powerful and dominate the 2-away schools. You don't have to know what crazy ability the other guy has if you first hit snaps his right arm and your second hit snaps his left arm. That was Ubogin's strategy until he was forced to abandon it due to Emperor Time clouding his judgment, and there's no way he can anticipate an enemy having an ability like Emperor Time. It's pretty much the most hax ability from a human character we know of, and it's competitve against even most of the Ants power in terms of how powerful it is.
