So the evidence is definitely not from only „this particular doctor“, but from a group of experts on the matter.
So are they claiming that this is actually due to the vaccine formulation itself, i.e. does this finding exclude the initial hypothesis of a Quality issue or a specific 'bad batch' of the vaccine?
Personally, if 3 health workers all go to the same hospital in a remote region complaining of clots, it's more likely that something local happened (as you say, QA, or any number of other sources).
Again, this is such a small sample and out-there group that it's not representative and there are many explanations that are more likely than "the vaccine causes blood clots".