The PRT would have to be insane to not want to poke and prod at her because of how dangerous and out of control Taylor's powers are to herself and, as far as I can guess, the only reason they haven't brought her in after this latest fiasco is their concern over how Taylor and her father might respond regarding Sophia.
And the fact they have no legal standing to do so.
She just grew uncontrollably, did a lot of damage to property and people, developed a new way to attack people, and seemingly used said new way to attack a law enforcement officer (or at the very least used it to threaten him and everyone else around them). It wouldn't be hard to spin that into good PR ("...our need to protect the public from dangerous and out of control parahumans..."), and there's not a lot Carol could do about that by itself.
Sophia gives the Heberts leverage, but there's only so far that can take them.
The Heberts don't know about Sophia. Armsmaster never told them.
As for the rest of it:
Growing uncontrollably is not a crime.
Property and human damage is a superhero thing. Also, nobody died. (If Taylor had killed Inago?
Then they might take her in).
It's not so much a new way to 'attack' people; her old way is much more effective. It's a way to communicate.
VERY LOUDLY.
Vicky can testify to 'provocation'. Also to Armsmaster trying to get her to go away and leave him alone with her brand-new teammate whom he intended to provoke into 'attacking' him so he could arrest her.
It would be a lot harder for them to spin it into good PR with New Wave spinning it the other way just as hard as they could. And New Wave would have a lot more to work with.
Also, about the only recourse they've got to getting her to come along is to ask nicely. The only fliers they've got on hand right this second are Aegis and Kid Win, both of whom are woefully underequipped to dealing with her right now. Starting a fight with the two-ton fire-breathing
intelligent dragon at the scene where she just ripped the arm off a dangerous supervillain (while Panacea's classmates are still on site) would be the absolute height of lunacy.
He is planning on figuring out whether or not it's possible, spending as much time as he can to get her trained, and maybe eventually let her fight Endbringers. He literally can't get her to fight Endbringers is she or her father don't want her to, so the easiest and safest and legalest and least problem causing way to go about it is to create a welcoming environment and let her know what she might be capable of so she wants to keep going once she's an adult and can direct her training and education down the relevant paths.
And if he led with
that, he might get somewhere, once she was human again.
Or not. She's very hung up on the 'poking and prodding' aspect.
On the other hand, can you imagine if Taylor came into the PRT building and Sophia happened to walk past? One of them recognises the other, and Taylor just dragons out on the spot. They'd be pulling out all the stops to contain her, and she just keeps getting bigger.