There is a sort of training zone - when the dog is able to pay attention to and willing to work to please you. If the dog is freaked out by something really scary - they're out of the zone. They can't pay attention to you. Anything you can do then, that calms them down and brings them back into the training zone - is not "training them to be freaked out" - so long as you stop with the calming / rewarding stuff as soon as they're back with you - and then only reward what you want. So I have no problems doing what I can to protect a dog from what is freaking them out (eg another dog that has attacked them or looks like a dog that has attacked them), and giving them pats and ear rubs to help calm them down, all the while being perfectly nonchalant about the scary thing myself.
The important thing is noticing when the dog is back with you and in the zone, so you can adjust what you're doing and make sure you're training the dog and not the other way about. Not always easy. But the thing with rewards - is the fallout (unintended results) from getting it wrong is not as bad, traumatic or dangerous as using aversives can be.
Testing whether your dog is in the zone: - can it perform any cues it knows well eg sit, shake hands, drop? will it take a treat. can it look at you and not the freaky thing. There's probably other ways to tell.
It doesn't really matter if they've gone out of the zone because they're really scared or really excited about something, you have to get them back in it to train. And usually the easiest way is to get further away from the object of their attention until you can be the object of their attention. If its something they like - you can use that to reward them, provided they can behave acceptably in gaining that reward - jumping all over the treat lady is not acceptable - but progressing calmly in her direction until she can treat a nicely sitting dog is ok (or give the treats to you to do same). You decide your own acceptable criteria.