The Game Master:
Although scared by your form, he does not talk.
[OOC]
Without the skill, you may shock and they may hold (freeze) or even submit (if it is their character or if the situation warrants it..."I'm not paid enough for this, man"), but you cannot force a disclosure. I'm double checking things, but that is how it looks.
If you do not mind me interjecting, here are my thoughts on the charisma skill. Much of this I am sure everyone already knows, but putting it down lets me order my thoughts better, so I hope you do not mind indulging me.
To start, nobody needs to have the charisma skill to perform an intimidation, persuasion, or interrogation. They can use their base Infl/Aura for it just fine, because those are tasks anyone can attempt. The chapter on character interaction states as much when they discuss how a character interaction is resolved (they specifically say a person uses those ability scores).
Having the skill allows you to use the charisma skill score in place of those Infl/Aura statistics. The charisma skill notes it is a skilled use only, and some people take that to mean that a person without the skill cannot perform character interaction. That is not so. It means that you cannot use your Influence/Influence with the -2CS unskilled penalty to make the roll (which would be a benefit for people with high influence and low aura if unskilled use was allowed).
So for Shield's particular event, it does not matter if he has charisma skill or not, it does not change what he can or cannot attempt.
However, Intimidation is not what Shield is actually attempting now. Intimidation is, as you note, to get someone to stop fighting, stop performing hostile actions, moving, etc. Having the goth stop struggling when Shield picked him up is an Intimidation effect.
But trying to get information from the goth is actually an Interrogation attempt, not Intimidation. That would be a separate roll from the original Intimidation roll that is keeping the goth from struggling.
Shield is trying to scare the goth into talking. That can be treated as simply flavor text (Batman does his interrogations in that scary manner, but Superman tends to be so nice that you want to give him answers, etc.).
However, it could instead be an indication of use of an Interaction maneuver with the Interrogation.
If Shield is trying to give the indication he will hurt the thug badly if he does not talk, then that could be a use of the Bluff interaction maneuver.
If Shield is causing pain to the goth while shaking him, that might indicate the Force maneuver. (I suspect that Shield would be very good at the Force interaction maneuver, but he might not want to use it for ethical reasons.)
Thank you for the indulgence!