I think that this is probably just casting for anything they think they may need. All casting is done via online submissions anyway, so it costs them nothing. This is probably a security blanket as the likelihood (unfortunately) is that some scareactors will go out with COVID.
It’s not something that Universal can totally control either as far as contracting COVID as casts tend to hang out after work, go to bars, etc.
IMO, Universal needs to invest in 15-minute COVID tests to do testing on everyone in these casts at least once per week.