For leaks there is rarely going to be a way to know for sure. So you have to evaluate whether or not you think it's reasonable given what you do know. We do know that they've done this kind of thing in other races. We do know that the party is funded by capitalist interests. We do know that the campaign didn't really put forward a positive agenda and therefore had to look for other ways to gain advantages. As far as the character of the people/party involved, I'm not willing to give them the benefit of the doubt knowing all the awful things they've been complicit in. Lastly it doesn't seem like it's some crazy infeasible or irrational thing to do. We're not talking about demonic sex cults or mind control or some nonsense. We're talking about political maneuvering through media strategy during a campaign. The objective was rational even if it was unconscionable.

As you said, they thought it was a good strategy to optimize their chances at winning. Not only did they turn out to be wrong, but the act of trying to instigate one of the only two political parties we're stuck with to take further right positions and possibly nominate a very right wing candidate is not an acceptable byproduct of the strategy.

Do I think we were headed in that direction anyway? Probably. As long as the parties aren't willing to address the fundamental problems with capitalism, the door will always be open to a right wing demagogue who knows the right things to say. But spending your effort to speed that along instead of, idk, working on actually popular social programs, certainly didn't help.