Personally I'd say there's a good chance he was taking advantage of them since they were old people to try and sell a higher priced item. If they bought that more expensive one they would be none the wiser b/c they never actually used the one on sale to see if it was any slower. Yeah, there is a chance he didn't know what he was talking about as well, but they will probably do a lot to try and sell stuff.
I know an older guy that I have to help out a lot with his computers. He likes to go to Best Buy for his new stuff he gets, and he fully relies on the BB staff "expertise". If I would have gone with him when he bought his router I probably could have saved him $30.
When I bought my first notebook from BB in 2005 they tried to sell me a $300+ extended warranty and he said a lot of people use it for getting new batteries b/c they end up costing $300+. I checked later and found plenty of places to buy a new battery and none of them were even close to $300+. My battery lasted until after that warranty would have went out and I sold the laptop the next year with the original battery that still held a decent charge... The sales people will do plenty of things to try and sell you more than you need to make the money.