Art theft is a pretty cool crime.
Although you could argue the law is not the best arbiter of mortality.
Functioning societies need every rule and law tested, and retested continually for suitability.
Also artworks can still be enjoyed post-theft through replicas etc.
And if the artwork is returned, as in this case, it's just a big win all round. Creating a new performance artwork in the process.
Compared to growing psychedelic mushrooms, I don't think so.