Aleric
In a 'moral' rubic there are three categories: moral, immoral, and amoral , yes ?
I would describe the Beast , qua desire, survival drive as amoral , a designation that denotes a thing as outside of moral consideration, not immoral which denotes a designation only applicable to rational conscious beings.
As has been stated the Beast isn't irrational , ITs actions are perfectly rational as applied to ITs survival. Indulging that desire one acts irrationally , foregoing the pain of known consequences in favor of the momentary hedonistic pleasure. Continuing to act in an irrational manner is immoral by definition of immorality as that which harms. Dismissing , ignoring, minimizing harm doesn't change the nature of the harm , but it makes it 'easier' to commit harmful acts.