Yes, the tradition does exist. A tradition is not the same as an inviolate law. It is not adhered to at all times by all men, but ti is by and large been practiced, as it would be by most men of good manners. Bubba is not one of those.
For the record, I think Bubba is a scumbag. Having said this, why should presidents give up their first amendment rights when they leave office? Frankly, it would have been a good thing had Reagan, Ford, Carter, and GHWB denounced Clinton big time. Their "good manners" helped to give the Rapist and Chief in Office.
That is denounce him when he was prez.