Thanks for the detailed feedback.

I still think blacklist vs. whitelist is an important distinction because it's a matter of inclusion. As @limacoin said above:

that would like to use the distributed computing power of BOINC, shall be obliged to invest first in setting-up a BOINC project, invest in the development of a working app and at the end be exposed to the approval of the community (If the project is whitelisted or not) waiting several weeks for the result of the vote.

A blacklist guarantees inclusion, even if only on a tiered basis, in exchange for the pain of setting everything up. Whitelisting means it's uncertain and a lot of people will never bother to do it in the first place since there's no guarantee of inclusion.