22 years is a VERY long time. No one is going to tell you not to apply if you reach out, so I don't think there is anything to be gained by bringing further attention to it.
I'd just make the required disclosure, let the past 22 years and the rest of your application speak for themselves, and let the chips fall where they may. People don't get secondaries for a variety of reasons, and more than half of everyone who do get secondaries fail to be admitted anywhere, so I wouldn't stress about that. Not getting a secondary is just a school doing you a favor, given how many people get thrown right into the reject pile as soon as they submit the secondary, and most schools are not so kind.
Unless your IA was for something like homicide, it's difficult to imagine anything from 22 years ago being the reason you don't get accepted anywhere. Good luck!!