I guess I am bothered by reading the Intelitec BIRD functions and thinking it ought to automatically see that there is house voltage available when there is too little chassis voltage.
Without even knowing about BIRD, I wondered why you need a dash ES toggle when apparently simply firing up the genset would couple the batts.
They could just say “if engine batt is too weak, crank genset first."
EDIT
I see that a disconnect solenoid must be part of the BIRD plan and that it seems reasonable to decouple them as you noted.
But with the constant use of the chassis disconnect by BIRD, perhaps the days of referring to the chassis disconnect solenoid as the EMergency Start (EM or ES) solenoid are gone, especially if this BIRD thing is in newer RVs.
With BIRD, the only time a person actually needs the ES dash toggle is in a situation where they know the genset is inoperable, the house batt is charged well, and the chassis batt is not, and, there is no nearby shore power available.