I'm sure card dealers deal with a lot A-holes and punks at their tables these days. If someone came up to my table talking down on my card prices like they could get better deals everywhere else but with me, I'd be acting like kiss my @$$ too. Are you sure that you didn't come of as a jerk to him first? Although every smart buyer does a bit of benchmarking, I don't walk up to tables and say, "hey, what do you want for this; I can get it for almost nothing somewhere else right now so you best to be giving me this stuff cheaper than these rip off prices." Dealers are collectors too, and they can get very personal about people talking down on their cards. Plus, it sounds like you were visiting a society with a different culture than were you come from, which could have also led to some of the misunderstanding. I notice this everytime I move to another part of the country. It definitely sounds like this guy misjudged you and demonstrated his realization of it by his apologetic behavior as you were leaving.
At the same time, I remember dirtbag dealers in the '80s trying to get over on kids and acting like they were holding onto silver and gold like we were supposed to worship them or something (I was a kid during the '80s boom era). It was like the wanted us to kiss their feet or something because they have a Mattingly RC or some other popular card. I had a guy waving high number '70s cards in my face like a fan talking about how I'll never complete a vintage set if I don't get with the program and pay $3-$5 for commons when I accidently pulled them from his $0.35 box of commons as a broke college student with no real money.
To me, 50% BV ($6.00) would have been a fair price to pay for that Morgan in [EX 5.0] condition, 30% BV ($3.60) in [VG-EX 4.0], or 20% BV ($2.40) in [VG 3.0] condition. Of course, I would have been looking for one for about $1.25-$2.50.