You can do that, but you're also going to drop the serving temp of any beer in the keezer to 32 as well. There's no free lunch.
And once you set it back to a higher temp, it'll likely take a couple days for the temps to rise in those kegs. How fast something cools (or warms) is a function of the amount--how much beer--and the difference between ambient temp and the temp of the material. So the beer already in the keezer will keep the inside environment "chilled" for a period of time, and thus the speed of warming will be slow.
One reason for cold crashing is to allow particulate matter in the beer to settle out. If you're crashing in the keg, you're dropping that particulate matter to the bottom of the keg where it will get sucked into the dip tube--and into the glass of beer you're pouring. Maybe that clears within a pint or two, maybe not.
**********
FWIW, there's at least one other reason to cold crash. I have a conical fermenter I can seal toward the end of fermentation so it self-carbs similarly to how bottle conditioning and carbing occurs. That's at 64-71 degrees, usually. But I can't completely carb the beer that way as the fermenter has a limit of 15 psi internal pressure. But beer absorbs CO2 more readily the colder it is, so by crashing as cold as I can get, I get as much of that CO2 in there as possible. I typically end up with about 7psi in that beer, meaning it's not a lot more to finish carbing it.
