Bitcoin mining takes up way too much power and as a results outputs way too much heat. Beside that issue, considering lead times and how long it would take to get those up there, by that them the hashing power would probably already be obsolete.
Did you read the wiki yet?
The major awesome thing about this is that the thinsats are extremely thin, and thus cheap to launch per unit of processing power. The heat output would be radiated into space, dramatic surface area works to our advantage there. Solar energy provides ongoing power at no cost, so as long as the thinsat lasts you would get at least some hashes (even if not as many as the next-gen thinsat provides).
Also, there is the matter of scalability... Satellites scale remarkably well compared to anything ground-based. At some point we start hitting the theoretical limits of ASICs, and the only way to compete is get bigger. And bigger means the cooling surface area needs to be bigger. At that point, space based (or perhaps lunar based) methods start looking much more attractive -- and they are certainly better for the environment.