The only exclusionary condition seems to be Guillain Barre Syndrome and even then there is a debate within the medical community.
Notably, Dr Fauci recommended against it for those with such a history.
I had a look into this because I've had at least one significant demyelination event (not Guillain-Barré syndrome), documented on MRI. The neurologists can't quite agree on what it was but but the favoured explanation seems to be Transverse Myelitis, the same thing they stopped one of the vaccine trials for (or at least that's what the rumours were at the time).
So I went looking for some info on vaccinations and demyelinating disorders. That's all sorts of vaccinations, not Covid ones, since any advice at this stage is based on experience from vaccinations in general.
There are studies comparing risk of experiencing a demyelinating event following vaccination
in the general population that show little if any increased risk from various vaccinations, so that's reassuring.
But I can't find any studies on the risk of a second event
in predisposed people, i.e. in people who currently have, or who have had, a demyelinating disorder.
So then I looked at how various patient organisations advise their members with regards to vaccinations and turns out their advice is all over the place, please take your pick. Broadly speaking opinion - and it does seem to be no more than opinion - divides into two lines of thought.
1) Get vaccinated.
Reasoning: both virusses themselves and vaccinations against the same virusses can cause demyelination events, those events are rare for both triggers, and getting the virus is generally more dangerous overall than the vaccination.
2) Don't get vaccinated (unless you're at particularly high risk of catching the virus).
Reasoning: if there's a good chance you won't catch the virus why run the risk of a demyelination event from the vaccination because while such events are rare they can be serious as anyone who's had one knows all too well. Rely on herd immunity.
Well, that's conclusive then. Not. I'm almost pleased it'll be at least 6 months before I'll be offered the a vaccine and have to decide whether to take it or not - though I rather doubt there'll be much better evidence by then to base the decision on.