I don't think we want one tag to apply to both a film and digital camera, and we can't just simply update the tag description, because then it won't apply to questions like this one which are about the film camera.
What we probably need to do is:
There's also a practical issue here that the Stack Exchange software doesn't let an orphaned tag exist - we'd need an actual question about the digital OM1 to keep it alive.
The above is I think uncontroversial. As a personal view and one that should definitely not be taken to represent the Photography SE moderators, I'm unconvinced of the value of model-specific tags in general; there's very little in photography which actually applies to only one model of camera. Looking at the 5 questions currently tagged olympus-om1, only one of them is really about the OM1, the rest are about film photography in general. Personally I would favour just dumping the model-specific tags which removes this problem entirely.