Well, those are Block Erupters, rather than Antminer U1/U2's - thus my asking if that's the one you meant - but, sure, you could do that. I'm pretty sure you can just as well leave the heatsinks on, though. These little miners generally don't generally even need active cooling, so immersion cooling seems overkill and messy, and the heat still has to go somewhere once the oil temp is saturated. But if you are going to do it, make sure you use a nice clean mineral oil - cooking oil and such is a recipe for disaster