How much time do you have in that make and model? How much is he willing to pay? How much do you know about the aircraft? Are you going to know what ADs to make sure are complied with and any mx issues specific to this aircraft?
I'd be more concerned with that than the owner's grammar. If you're not familiar with the aircraft and he's not familiar, it's still your hide when he puts it in a ditch.
I'd be leery of flying an unfamiliar aircraft above an unfamiliar person. Don't be in a rush to log hours at the expense of your personal safety and certificates.
Hector, you really need to stop adding your opinion when you've never been in the situation. It's not helping your cause in any way, shape or form.