Whether the administrative appeal against the January 2015 decision was admissible despite the available opposition remedy.
No. The January 2015 decision had to be challenged first by motivated opposition before the unemployment insurer; direct appeal to the cantonal social insurance court was unavailable.
Under Art. 56(1) LPGA, an appeal is inadmissible against decisions that can be opposed before the social insurer. The insurer had issued a decision on January 2015, so the appellant had to file opposition under Art. 52 LPGA and then, if necessary, appeal against the opposition decision.