That's fine: I'll let Frozen Princess write in what Erin's reaction to Schro's interjection is, before Blair and Alexa's own rebuttal and then post for Schro.
I should make a note here stating that Marko is a rational guy and he is a student with no experience dealing with a hostage negotiation: even if he heard of an ongoing back robbery, he figures that his presence there would only make things worse. He does not know how he should act if someone threatened someone else's life like that, for one, but further: he has not even had a public appearance yet. People don't know that he wants to do what's right, so he has no knowledge of how anyone might react if he suddenly showed up in his superhero persona on-site. Any by anyone, that means mainly the robbers, who might just do something drastic and shoot the hostages, as well as the authorities, who might think this unknown person is in cahoots with the robbers and try to pin something on him.
Another thing to consider is that Marko wants to build himself some weapons, before he goes out on his debut and stuff- something which will take time for him to build, since he only has a (for his potential) low-end forcefield that could resist twenty shots in quick succession before it flickers out and has to recharge.
And Amaya being who she is, she will take all the time that is needed (days, weeks, months) to make sure she nestles into The System without fucking over the little man or pissing off the Powers that Be too much. At the start anyway: she fully intends to do wondrous things that will help the little man more than The Man.