Bromeliads are pretty tough, I don't do anything to protect mine, but then we rarely go down into the 20's here. There can be so many reasons why one plant sustains damage and why another doesn't, moisture, frost, wind, heating from morning sun, age and condition of plant...etc. Pretty good that mid 20's for that duration your mounted bromeliads did so well. We only went down to 30F here two nights, 3 hours first night and 7 the second night, third night we stayed in mid/upper 30's, my bromeliads were not fazed a bit, even the mounted.
As far as a pup emerging, I certainly would say since I've had pups come out from what I thought was a dead bromeliad for other reasons, then yes it is very possible. Mom plant protected those little nubs waiting to emerge.
