Frozen as in like how assets can be frozen by governments? This is completely impossible. It's possible for them to monitor your known addresses, however, and track movements. If they somehow order you to not move any Bitcoins, they can't stop you, but they can punish you.
Bitcoin is unique because of it's decentralized. If government decide to control bitcoin, bitcoin will lost as decentralized currency and government usually will apply tax on bitcoin just like fiat.
Well it's just same as fiat but the different only bitcoin is on digital form !
there is a perfectly easy way to "freeze" the financial assets of almost anyone by a government; simply put the suspected persons in jail. they dont have to monitor, they can actually prevent you from having access to any device (because you are locked in a box) and other people that you could communicate your wishes to. it takes very little in the united states to enter this legal state; simply "resist" arrest and you just bought a cheap ticket lol.
the only time a government can regulate a thing with little effect despite the penalties, is when that thing is so ubiquitous its too hard to police (jaywalking and marijuana). bitcoin is neither of these.