To be fair, it’s been a longstanding rule with Republicans that whatever they accuse others of is merely a projection of what they’ll do the moment they can get away with it. Whether or not they would try to steal an election isn’t even a question. They’ve as much as admitted it. The only question is whether or not they did. I’ve not seen any evidence to that effect, and I’m not presuming there is any, but it would be idiotic not to at least contemplate the possibility.
Without calling into question the broader possibility that malfeasance did occur, I don’t feel like this argument is particularly credible.
Suppose you were to engage in some form of straight up ballot stuffing? Why then would you make them bullet ballots? Why not vote straight ticket Republican? Straight ticket ballots are not unusual - even less so then bullet ballots, apparently - so you’d draw less suspicion, and you’d get the benefit of lots of extra down ticket votes.
If someone was going to cheat, what benefit would they gain from cheating this way?