no, if its your bike for 40 years and you want to decorate it, there is no ethical question.
It's officially no one else's business.
My Raleigh Grand Prix still says Raleigh Grand Prix, it just says it nicer than the original decals that I never liked.
(The paint is still original, just stripped the old worn decals, polished it up, tipped the lugs and put on new decals)

If you try to make it something it's not and especially sell it, that would be different.