Sounds like they are basing it on the one real-world fusion reaction we see every day that is 93 million miles away. Plenty of X-rays come out of that reaction. Fusion in the core of that reaction does produce gamma rays, but those frequencies get slowed down before they reach the surface.
Aneutronic fusion is the Holy Grail of Green Weenies. I doubt very much they’re talking about gamma rays; almost all interactions produce photons, in particular both hot and cold fusion. They die off exponentially and don’t generally produce long lived products.