In an election between the two parties I think that would be a very likely narrative but in this case it's the primaries. And (as others have mentioned) neither primary has really had anything resembling a competition at this point so it's more or less irrelevant to the result (most likely).

conspiracy theory get more imaginative.

For example, you can then pose the conspiracy that the fact it was Russian interference conspiracy was a conspiracy to justify more social media policing during the real election.

Perhaps but why would downtime increase policing? Something like a large scale fake news campaign (i.e. basic deep fakes or something) is easier (generally speaking) to pull off and would be more likely to cause increased policing that a short outage.

There are probably more MAGA's on Facebook platforms than TFG's Truth Social. Either way it's going to start a few conspiracy theories.