I don't think government contracts have anything to do with it. Despite all the sky-is-falling talk, those are multi-year, open ended contracts. DHS includes ICE, Border Patrol, Secret Service, and the Coast Guard. Figure a thousand rounds a year minimum per gun toter just for qualifications, plus another 200 boxcars full for the various training academies which are running schools full of eager newbies and you've got a lot of ammo. Nothing new. Besides, if DHS was planning for some kind of large scale uprising to put down, they wouldn't be buying pistol ammo.
The fact they're hollowpoints doesn't mean much, either. I carry a .45 and for quite a few years our practice ammo switched from ball to Ranger XST 230 grain HP, even though our issue was a different brand of HP. For some reason the Ranger was cheaper than ball those years.
The reason there isn't any .22 ammo is that everybody buys it as soon as it hits the shelf. Sheer panic. Eventually the market will be saturated - it will just take longer for .22s. Then a bunch of folks will be looking at a stack of ammo they won't shoot and a stack of credit card bills they can't pay.