I think he was morally justified in shooting the thieves.
If I was on the jury I would have a hard time convicting the man.
He may be morally justified but, the LAW will not see it as a justified use of deadly force - neither SYG or Castle Doctrine can be invoked for this one.
No doubt they deserved it but the chances of him getting off seem slim based on what I read. But then, I don’t know how PA law works as far as defending your property. Sucks that some folks work to attain something and others assume they ought to be able to take whatever they like. Makers and takers.