That is only first order effects
I do not see this accounting for Life Sciences people going where the funding is which is something they do.
That whole industry is based on that. There are very little permanent contracts even in the commercial part of it, it is all fixed term, subject to funding. The moment the funding goes elsewhere the people go with it. Most of them have little "roots" anyway and a very large proportion of them are from Europe because UK simply does not produce enough degree educated life sciences professionals.
This does not seem to account for their exodus and that exodus will happen. It is a given considering how that industry is organized.