As far as I understand, they claim think that since spike proteins in the actual virus particles are embedded in the particle (as opposed to “free”/”detached” when produced after getting the vaccine), they do not accumulate in the tissues, at least not to the same extent. Possibly, after a virus particle has been destroyed, some of its spike proteins circulate freely (or attached to some smaller segments of the virion) and then can get into tissues and accumulate.
As far as I understand, they claim think that since spike proteins in the actual virus particles are embedded in the particle (as opposed to “free”/”detached” when produced after getting the vaccine), they do not accumulate in the tissues, at least not to the same extent. Possibly, after a virus particle has been destroyed, some of its spike proteins circulate freely (or attached to some smaller segments of the virion) and then can get into tissues and accumulate.