I am not afraid to talk to an old guy. Competent to make a purchase is kind of a funny thing. Some skills are rote. It is like the person who has Alzheimer's who can tell the name of their best friends dog in 1939 or perform a skill they have done forever but can't remember their grand daughter isn't really the daughter
So yep I'd say hello and ask a question or two. Lol old guys are always hitting on me in the grocery anyway. I must look like a good catch for a 70 year old dude
if he seemed confused I would get the manager and then use our two heads together to figure out the best thing to do.
I have no issues with judging the rudeness of running off to a msg board and talking about old people and stink. But I am sure you will judge me for that lol