Regarding blindspots:
Esper powers indeed aren't a blind spot in general. Not saying there won't ever be an Esper power that isn't one, but in general they aren't.
Every time she grants someone esper powers the worm precogs have to adjust for the new power. Sometimes a little, sometimes a lot. Depends on the power and the person she grants it to.
So, we can be almost certain that Mental Out isn't a blindspot for Contessa: she's being precogged by Dinah at the moment, among other things.
With regards to Cauldron, and what they're doing with regards to Nozomi, there's really three different possibilities:
Possibility one: Cauldron is aware that Mental Out can grant powers. They picked up fact by Clairevoyant, and are currently running a path to make her hand out as many as possible. Coil is permitted to attempt killing Mental Out because that's what the Path needs to get Mental Out mass producing powers. Expect something deeply traumatizing in the mid to near future to get Nozomi willing to work with Cauldron.
It's actually very difficult to recruit Mental Out through any sort of dirty trick to Cauldron: she can read minds, so they can't really mind control her, mind control people at a distance, so if they kidnap her, she has to be kept away from other people, and the Power Curriculum Program involves her tampering with people minds already, so anyone she empowers could be a sleeper agent. So they'd have to keep her in a 500 meter exclusion zone, and have kids walk in, go through the program, and leave, all with MO still trapped there.
That's a nightmare to organize, and even then would fail the first time Nozomi produces a power that would immediately get her free. No, if they want Mental Out to help them, easiest to have things just so happen to put her in a state of mind that would have her cooperate. Even then, it would come out if/when Mental Out reads Contessa or Doctor Mother's mind.
Possibility two: Cauldron is not aware that Mental Out can grant powers, but whatever paths that Contessa runs to maximize power users consider the Power Curriculum Program the equivalent of parahumans. Contessa is doing the same thing as in Possibility 1, but isn't aware of why at this point, just steps on the path.
Functionally identical to possibility 1, but less risk of sudden furious Mental Out, as while Contessa did a bunch of sabotage, she didn't know it was targeted at Mental Out, so Nozomi can't find out about it by reading minds.
Possibility three: Contessa's paths have been structured/worded in such a way that Mental Out's power curriculum program falls outside the stated remit. While Cauldron would care if they knew what she could do, Cauldron doesn't, and however Contessa's paths are running, they aren't optimizing for espers, because they're optimizing for "parahumans".
In this possibility, cauldron isn't paying Mental Out any special attention, because "cluster trigger with short ranged but powerful mind controller, some tinker ability, and an unknown thinker power" isn't likely to be useful against Scion.
Personally I think it's probably that possibility three is the case. It explains why Cauldron let's stuff like the last chapter happen, without having them be in an automatic antagonist position.