Force play question, right to occupy base.

[RKBUmp]

Does runner lose the right to occupy the base they are on immediatly upon the hit, or only after the succeeding runner has actually reached the base?

Situation presented to me,

Runners on 1 and 2, ground ball to F6, runner at 2 never leaves bag, F6 runs to 2nd, tags lead runner standing on bag, then tags runner from 1st prior to reaching 2nd.

I say 2 outs, runner on 2nd was forced to vacate the base on the hit. Umpire that presented case called 1 out, runner on 2 not forced to vacate until succeeding runner reaches 2nd.