A couple FA's told me the curtains were removed because of the single operating certificate. Southwest has an FAA certificate specifying a single-cabin configuration. Curtains created a minor language question which they pre-emptively resolved.
FL serving liquor minis in BC without caps was part of the same better-safe-than-sorry rule compliance. Seems a bit questionable - since legacies sell capped minis in Y.
I have no basis to confirm or refute any of the above hearsay.