Afaik, that can be introduced into court as well. If spoliation of evidence can be demonstrated, evidence of that can be brought into court, and the jury can be instructed that they are allowed (but not required) to assume that the evidence was unfavorable to the party that destroyed it.

That they're willing to admit it is extremely concerning. It either means they think they can get away with it, or that whatever was in the texts is worse than what they're being accused of. Neither is a good thing for a functioning democracy.