Finally got some answers. Both FSDO Inspectors I reached (at different FSDO's) said they would investigate the situation to determine just what happened. They both made clear that they would be investigating, but that any FAA action would depend on the results of the investigation beyond the bare bones facts described. Based on that investigation, one wrote:
The other said, "I'd be looking to find out if this was intentional or just stupid." He said that this is a technical violation with no direct safety implications, which puts it on a lower level of interest to the FAA. He went on to say that if it appeared intentional (i.e., that the pilot knew it was wrong but did it anyway), he'd check that pilot's records and then process it in accordance with the EDT, which, depending on the pilot's record and attitude and anything else that turned up in the investigation, might result in anything from counseling to administrative action to an enforcement action with a suspension under the EDT criteria. He said that if the pilot simply didn't understand the rules, and had an otherwise clean record, he'd take the pilot in a room somewhere for counseling, and then file this in case the pilot's name came up again.
And, FWIW, if you've read this thread, you won't be able to honestly claim you didn't know better.
So I'll stick with my original advice which was to fly the wallet, pay your own expenses, and be a gracious guest the next time they take you out to dinner someplace pricey or for a round of golf where the greens fees are in three digits, and then you'll never have to answer that question from an Inspector.