Employer Match

Is there any scenario where it is ok to have a match in a plan only for a select group of employees?

Yes. Class specific match groups are written into plans all the time. Usually done only for regular match (not safe harbor or its variants). As long as testing (coverage, ACP etc) passes its fine. 

Right to match is a BRF that must also pass (a)(4) testing.

11 minutes ago, JRN said:

Right to match is a BRF that must also pass (a)(4) testing.

its already subject to coverage (typically done via 410(b), though I suppose could be 401(4)) so if that passes BRF will pass. I've never seen separate BRF done just for the right to match.