This is likely beyond the scope of the specific Walther pistol being discussed here, but you hit on a couple things that likely should be discussed. I'm not sure I understand how an optics capable pistol, even if not equipped with an optic, could increase liability, nor what policy questions would be raised. Do you mean officers would question why they are not given an optic to go with the pistol?
While there are issues with optics (primarily cost and the strengths/weaknesses of the specific optic chosen), if I were in the position of choosing a replacement pistol for my agency right now, it would be optics capable even if I could not immediately implement the optics. It is much more cost effective to buy pistols with the capability to grow into optics at the armorer level at a later date than to deal with the logistics of pulling in service department guns out of cops' holsters to be direct milled.
Equipping any pistol with an optic certainly does cost money, plus there is training necessary for transitioning officers to the optic, but ultimately optics allow increased threat assessment capability vs. irons and likely increase hit probability for most shooters. This increased capability, particularly in terms of threat assessment, should lessen the likelihood of a reasonable mistake of fact shooting (i.e. mistook cellphone in suspect's hand for a gun). As far as misses go, there will almost always be a lawsuit brought if that miss causes collateral damage/injury, regardless of sighting system.
I'm sure some administrator likely will ask specifically for a non-rds capable version of a pistol that natively has rds capability, but in my opinion that request is ill advised and not worthwhile for the manufacturer.