Fusion is an energy source. Like any other energy source it's automatically also a weapon. All energy sources have historically saved many more lives than they ever cost, including nuclear power.
Unfortunately, despite the fact that even current nuclear causes less deaths per GWh than anything else including solar, itβs also the only power source currently offering humanity a self-made extinction apocalypse.
(Also the heat mirror was debunked twice by Mythbusters, as referenced in your own link).
True, but that's only because it's a really good power source. For instance, it's also what allows us to have working devices outside our solar system, and for similar reasons.
Any really good power source will have this problem, as will a great many other technologies, should we have them.
And even solar power is a weapon:
https://en.wikipedia.org/wiki/Archimedes#Heat_ray