A copyright protects an actual piece of work. If we were to say the remakes of these shorts were public domain, then we'd also have Husbands Beware (Brideless Goom remake) and Rip, Sew, and Stich (Sing a Song of Six Pants). I could be wrong, but I don't believe the copyright extends to the content of the actual object (film, or whatever it may be). Meaning, a copyright for Malice In the Palice isn't the same copyright for Rumpus In the Harem, regardless of stock footage used.
Anyone know how the copyrights lapsed on these 4? I'm sure there's a thread somehwere here about it..