Earlier quoted context omitted.
At 50:00 Elon agrees that Trump's "Space Force" is a good idea.
Trump isn't the first person to talk about having a military presence in space, that was pretty much the main reason for the budget going into NASA early on. And, well, aside from the bias Elon would have where he's developing what will likely become the most successful for-profit space business in history - which I'm sure he's aware of that bias, it definitely is a good idea to be prepared to defend against bad acto…
The U.S. even researched (and in some cases developed prototype) weapons for space, not just SDI/Star Wars stuff either.
Stuff out of the Future Weapons Office, some of which can be found in the declassified "The Meanderings of a Weapon Oriented Mind When Applied in a Vacuum Such as on the Moon" like 'a spin stabilized micro gun', 'spin/fin stabilized sausage gun', 'sausage gun #2', 'directed gas weapon for close in fighting', 'spring propelled spherical projectile', 'gas cartidge gun', 'gas operated needle gun'.
The Soviets even sent conventional firearms into space like the triple-barreled TP-82, 2 barrels in 28 gauge and a rifled barrel in 5.45x39mm, although this was more for survival upon re-entry in remote Russia. HOWEVER they did develop a prototype laser pistol in the 80's that used a pyrotechnic flashbulb for disabling optical sensors on spacecraft, basically let a cosmonaut out for an EVA, get within 20 meters of the sensor and fire.