I can see this being useful as a canary to let you know someone has acquired unfettered access to your device, but it doesn't seem very practical for high value targets (who cares about $5 of bitcoin if there's far more valuable info to steal), or if the attacker decides to steal the bitcoin wallet file and only transfer coins a few weeks later after he's already taken advantage of the other info he got off the target device (and by then you probably already know you've been compromised anyway).