Yes and no. Even with Bitcoin and especially Monero, such a block is symbolic unless it targets exchange wallets which indeed can be frozen (not your keys not your coins). If it is a non-custodial wallet, the user can use mixers so send to another wallet or exchange while breaking the linkages to the blacklisted wallet. With Monero, this is even simpler since it is a privacy coin designed to make transaction tracing difficult.
In the case of Grin, like for Bitcoin and Monero, authorities can freeze assets at exchanges but not on local wallets. As of yet, Grin is privacy preserving, meaning no amounts are shown, but transactions are still linked and traceable.
At the moment, work is being done on Coin Swap implementation for Grin, after which Grin transactions should be much harder to trace, making Grin transactions more similar to Monero. Also CoinJoin/Mixers are being researched .
Furthermore, Grin, has no addresses and uses Tor which makes it hard to link an IP to a user uses Dandelion (scroll down to ‘Dandelion in Grin’), which already combines transactions before adding them to the memory pool and uses cut-through which also makes it harder to link inputs and outputs. So in the case of Grin, only if you have black listed exchange wallet you can be targeted by governments. With Grin identification is difficult unless you voluntarily perform KYC and use that exchange address for purposes that might lead you to be black listed.
So Grin and other privacy protecting or preserving coins are hard to sensor by government, only exchange wallets are an easy target.