Being Bulletproof is a sliding scale Mr Zoat.
As are Sniper Rifles.
Name a partially bulletproof person in DC. It's usually all or nothing. Sniper Rifles - which the military already has - and therefore just needs consistent, not increasing funding, work against things like bulletproof glass, but bulletproof villains are still bulletproof to the point they don't work. They don't NEED significantly increased funding to deal with supervillains. Doesn't mean it won't be useful. Crucially, Horne isn't advocating decreasing funding - he's not anti-military, he's just against expanding funding when an already well-funded military isn't showing results.
Though, if there wasn't a war in Vietnam/ Iraq, it might not actually be that well funded.
We're not actually talking about having 10 guns in the entire military. We're talking about increasing military funding not doing much if it's not run well enough - the US spends $617 billion yearly on military expenses, with an extra $99 billion in case of war. Spending an extra $100 billion isn't gonna make much of a difference when dealing with supervillains, and the US can't afford to pay themilitary even twice as much as it already is.
The problem is that this is the DC military., not the actual US military - It's not well thought out, and they don't find super geniuses to come up with their tech. Instead their tech is modern tech, and they don't find Ex-criminals, like the actual US does/ did. (E.G. Werhner von Braun).
They're at the point where they could pay Mr. Freeze / Captain Cold billions to come up with affordable freeze guns, and still save money compared to what they spend now to come up with the same tech. That would probably stop them stealing, let them live in luxury, and deal with whatever issues they have (e.g. saving Nora Fries). Mr Freeze would be so much easier to control if you have him millions of dollars of funding to save Nora and any resources he needed.
Same thing with Zeta tubes. You want teleportation? Fund whoever that tech belongs to to find ways to make it affordable, and suddenly you've just got the ability to drop bombs into the middle of whatever buildings your enemy leaders live in. Even if it takes too long to set up, you could airdrop a zeta tube, and then have any amount of shock troopers step out.