We have interviewed and hired plenty of people even older (age is not something ever known/discussed and illegal to factor in - but it isn't hard to make a good guess anyway)
senior engineer could be a project manager who never wrote code.
i remember this because it is one of the faw 'no' I have had where it wasn't proved the person would be bad at the job. Normally the no hire signal is because the person would obviously be bad.
Why, after interviewing them, were you unable to figure out if this person can still code?
Because we didn't ask the right questions. We changed the process to require some questions. Which isn't perfect either, but we don't get months to interview someone so.