Usually the following configuration for unused opamps is said to be troublesome, even for rail-to-rail input & output (RRIO) opamps. Nevertheless, it is attractive because it requires no additional components.
The reason seems to be anomalously high current consumpion due to output saturation. When the input offset voltage has the "wrong" sign, the output would need to go to a slightly negative voltage to reach equilibrium, thus saturating because it cannot achieve this.
What does this mean and why would it lead to increased current consumption ? After all, the only load on the output is a MOSFET gate which will not cause any appreciable current to flow. And all the internal gain stages are anyway operated with a constant supply current, no?
Another approach to formulate the same question is: Why is it deemed ok, to abuse such opamps as comparators, which almost always uses an open loop configuration and causes output saturation? Isn't this usecase equivalently "bad" as the one drawn above?