I'd rather ask someone "in contact with aliens" a math question, where we could check the answer, than a question about the direction of technology which 1) gives them a binary choice (easier to fake), and 2) could result in some labs burning years of time, even if they don't blow themselves up.

Hence the last part of the question, "Why?"

I doubt even someone with a PhD in an unrelated field could bullshit the experts in fusion research.

"Inertial. Magnetic will be more inefficient at higher power levels, because a particle you haven't discovered yet will dampen the reaction if you use magnetic confinement. Ultimately it's because the string coupling parameters for the 3rd-dimension/8th-dimension interaction are stronger than for the 5th-dimension/7th-dimension interaction". It's an explanation that looks like probable made-up baloney, but can you be sure? Can you (or anyone) disprove it?