How is that different from an asset in a bank account? What matters who controls the access to it.
This doesn't work with banks outside a court's jurisdiction. That doesn't stop enforcement.
We already have tools that informally designate tainted versus untainted wallets. Incorporating that into the law wouldn't be that difficult nor, I suspect, controversial.
Enter the exchange control laws from the 60s that still limit capital flow out of SA.
1m ZAR per annum per person(~70k USD) this includes things like Netflix subscriptions, Amazon orders etc.
As you say, there was a delay, not a stoppage.
I suppose the issue will be getting you paycheck $$ from South Africa into Coinbase (or wherever)