I find this hypothesis slithly more plausible than a pulsed radiofrequency/microwaves attack where the way this could alter white matter seems unclear, but especially given a precedent [0] both are good candidates.
This is compatible in my view to a russian interference in the midst of warming relations between Cuba and the US/Canada. The diplomats seems ro be the only members of the embassy to be affected and the russians know how to not leave their footprint when they don't want to (e.g. not Novitchok or Polonium).