This is pretty easy to consider.
If there is a disposition towards prothrombitic activity following MRNA vaccination, and the idea that it's subacute in so many people, you would expect to see it be acute in some of that population.
At this time there's no data to support increase number of blood clots in the mRNA vaccine crowd. And there's in fact data that shows no difference in the general population.
Another study that could be determined based on his hypothesis, is a clinical research study that evaluated spike protein subunit expression on the vascular endothelium itself along with tagged platelets to show aggregation following activation.
He doesn't say what kind of d-dimer elevation he's seeing. But quite easily to begin with d-dimer is not a clot specific test. The number of different things including pregnancy results in an increased d-dimer. Pregnant patients, despite having months and months of elevated d-dimer, do not commonly develop pulmonary hypertension or other chronic vascular compromise.
It is worth noting that pregnancy is a prothrombitic state but it is for many reasons independent of d-dimer readings.
So you don't have an increase in clots with the mRNA vaccines.
If he's right there is an increase in d-dimer and it would be interesting to know how high and how transiently.
Transient d dimer elevation has no backing That you've now developed permanent vascular compromise.