Responsibility seems to strangely flow only in a single direction in the top echelons of the Tempest kingdom: Rimuru went to a bar for a night, and has to grovel before Shuna and Shion, begging for mercy. Yet when Shion shamelessly got so drunk she passed out in front of an allied nation's king, nothing at all resulted from that.

So, yeah, I very much agree with Gazel: Rimuru is lacking in regal bearing.