Castle doctrine extends from your home, to auto, to your own business if you own it or have permission.
Getting your GWL isn't a big deal and I would highly recommend it….. have him take a look at gacarry.org.
This owners actions got his dog killed....I treated my last dog like family and am an animal lover....My dog came to my shop 6 days a week with me and I trusted and protected her like I did one of my own...this guys neglect in securing a dog like that is an issue....he didn't have to escalate...
This guys actions got his dog killed...NOT the officer....I felt like this was a totally justified shooting....I would have done the same thing....that 100lb dog takes a jump at me and its going down too...had this guy not shot his mouth off, gotten involved in OTHER's business...he will still...
Given his attitude of respect towards you I believe that you REPAYED the respect by allowing it and in kind, you walked away without a citation....
I think you did just fine....
Your car is considered an extension of your home...so is your business if YOU own it...
but It would be a good idea to get a permit anyway....my .02 cents.
To the OP:
I hate that this happened to you. I too have been in a similar position and I know how exposed and scary the situation is. I have read every post in this thread and there is a significant amount of really good arguments in this thread. Really good stuff and I know you have guessed...