The kitchen faucet (pull out) "blew out" when the water was turned back on, after the hot water heater was installed.. . should the lines have been bled for air, or was it most likely the faucet being old and worn?

What exactly happened " "blew out" Air in the lines is bled via that faucet as you open it.

Definitely a faulty faucet. Changing the water heater out, whether air was bled from that particular faucet or not, would not be the cause of the problem. Sounds like a fluke of bad luck on your part(or the plumbers, lol). Changing a water heater out is just that, and nothing more. Any fixture in the home should be able to withstand turning the water off and back on, and if it cant, it was in need of replacing anyway. I would find it hard to believe that the plumber was at fault, so take it easy on him. These things happen, it really sucks when they do, but they do.