Sure, the attraction to blackhats of cyptocurrency is that it’s a ripe target accessible via the internet.
Not sure how that connects to the TXtenna project or other contemplated or current mesh projects. My understanding about it was that the goal wasn’t to convert it to cash value, but to better allocate scarce resources on the mesh - or something to that effect, That would tend to discourage those seeking to rip things off for the money. Leave out the possibility to cash it out of the system and you greatly reduce the potential attractiveness for hacking, a very good reason to avoid that option altogether, rather than institutionalize it.
Allowing essentially the same thing to happen with gold or silver, however that value might be cashed out of the mesh system, would make it even more attractive to bad actors than cryptocurrencies are.
Then there’s the fundamental problem of privatizing what is supposed to be a commons to turn it into a private profit center. That would tend to undermine the concepts that mesh is based on.