Not so easy to check is you platform can launch BOINC. There could be invisible restrictions.

Also, if your target is increase BOINCing users, then I don't think that direct prohibition could help in that situation. Better solution could be show user that he could earn more if he begin using BOINC manager, like that:
Earned 0.1 GRC
Could be earned if you use BOINC manage: 0.15 GRC setup link and instructions
It should be fair. But we cannot calculate gridcoin rewards precisely.

Or give user reward for installing BOINC manager, joining pool, reach a milestones in BOINCing. But now I don't know how to do that.