401(k) Steve, there are several issues here. As MWeddell states, you will need to look at the terms of the plan document. In particular, does the plan document require a last day of plan year service requirement for receiving the match?
In addition, as MWeddell points out, unless you can find a permissible disaggregation scenario (i.e., QSLOBs), the matching portion of all the plans in this controlled group will have to be aggregated for purposes of passing 410(b) coverage testing (with this LLC's participants showing as not benefiting), and for 401(a)(4) testing for contributions (in this case, the 401(m) test.)
MWeddell, question for you: Is BRF testing really needed under these facts? In essence, the BRF test would go back to 410(b) ratio test for current availability of a BRF, and then a nebulas effective availability test, which seems to go back to some version of 410(b) testing. If you pass the 410(b) ratio test for coverage, you will likely pass the BRF testing under 401(a)(4).