A DB plan was add late in 2005 to an existing 401k-PS plan and it's intended to be permissively aggregated for testing and subject to the gateway (don't qualify for the exemptions from gateway). There were some modest match contributions made on a more liberal basis (eligibility wise) than exist for the PS plan or DB plan. Do the participants that got these token match contributions but who are not eligible for the PS or DB contribution/accruals have to get the 7.5% gateway ? Or is the fact that 401(m) testing on match contribution is mandatorily disaggregated from the general 401(a)(4) test enough to avoid giving them the 7.5% gateway (on an aggregated allocation basis) ?

gateway applies to nonelective contributions
a match is not a nonelective contribution
a DB accrual is a nonelective contribution.

so, if he received a nonelective he has to get the gateway.
if match only, then no gateway. if I understand your question correctly

Thanks Tom.

Is a Top-Heavy contribution considered nonelective?

generally yes.
however, since a match can be used to satisfy top heavy, it is possible that some people might satisfy top-heavy without receiving a non elective contribution.

I have seen some documents refer to match as a non elective contribution, but I think that is a confusing use of the term.