How easily can table salt be contaminated?
No foodborne illness is going to be able to live in pure salt, in fact even low concentrations of salt will kill most foodborne illness organisms - which is why salt is used as a preservative. However, that does not mean that it's a good idea to touch the salt with contaminated hands because:


You could contaminate the container the salt is in, anyone touching the container could pick up the illness and transfer it to themselves or the food
If there was a significant piece of food stuck to your hands when you touch the salt the piece could fall off into the salt, and any part of it which does not come in direct contact with the salt could remain contaminated. If you came into contact with that piece you could pick up the contamination
From a non-safety perspective, getting chicken juice in your salt is going to make it stick together and get nasty because of the moisture


When I prepare a chicken for baking I do the same thing - I pour salt and spices in a bowl and then pinch it out of that bowl before rubbing it on the skin. When I'm done I throw out any remaining mix and wash the bowl. When filming a show like the food lab they do the same thing - everything is going to get cleaned afterwards, so if the bowl got contaminated it doesn't really matter and the salt is not going to be re-used. 

The takeaway from this is that it was fine in the food lab, but it would not be fine at home if your were using your main salt container.