Mike
We visited BW on our last trip. We told the guard we were there for dinner and he just waved us through. We had already eaten, but we just wanted to have a look round and a drink. So it was still a legitimate use of BW IMHO.
We were not trying to get a parking advantage for a visit to EPCOT, which is what seems to cause the upset I think.
We were not asked for PS numbers etc.
I can see how off site guests parking there could really tick you off if you are shelling out big bucks to stay on site or you are a DVC member. However, if you intend to eat at BW later that day I personally wouldn't have an issue with you parking there as it would seem silly to go all the way round when you want to eat.
We did that trip after eating at Beaches & Cream, and that walk back through the park to the EPCOT car park is a long one!!
I would see your situation as, you are using the facilities of the BW during that day, and by eating there, have justified your car parking.
Then again, I niether stay on site or have DVC membership so my opinion doesn't count for too much.
I'm just using a bit of common.
Cheers
Craig