I think there are different forms of exosomes. And some of them may be a natural communication system.
Some of these may have evolved to viruses.

The formation of such exosomes is a very complex process, that requires many cell-components to activate.
So assuming there is a connection between EM-radiation and viruses in the form of exosomes, these components need to become active via radiation.

What I usually see in the damage from radiation is more a process of de-activation or destruction of certain cell components. At least that is how I understand it. So I don't think that this would directly activate such cell components.

What might be activated is a decaying process that is similar to cell death. The grape-plasma experiment shows pure destruction that may trigger cell death processes. But what functioning exosomes would cell-death produce? Personally, I don't think they would look anything like the corona-viruses. But more like skin-cancer or something.

Whether it is true or not, I don't think that this research-paper is any good. It does not seems to be made by scientists, and in its timing it could be some trolls that want to write something about what David Icke told.

I don't think that the exosome idea is completely bunk, but let me describe how a good scientific paper looks like.
Research would first show a relationship between cell-changes and different types of non-ionizing EM-radiation.
That would be a complete deal-breaker already with lots of follow-up publications.
While the CIA has published some on it and others, it did not give much reactions, though. Next the research may show that these cells form exosomes.
And the following step would be the similarity between some of these exomes and viruses, maybe even identifying which virus.
Preferably each biochemical process that is activated needs to be detailed in how it reacts to the EM-radiation. Also we may look at the different types of EM-radiation and its relationship with the biochemical process.

See also on covid19
https://microwavenews.com/news-center/time-clean-house