Criticizing the couple's decsionmaking (with benefit of a retrospectroscope) may be easy but ignores the extent of information that was available to those in the field at the time.
We left White River Tuesday. The forecast as of Monday looked great through Thursday. How much value does any forecast have in mountains 3-4 days out? Certainly not much in Eastern mountains. Is Washington different? The Alabama couple presumably had this information, for what it was worth. If that information alone tells you to stay home you may never climb on Rainier.
We camped Tues PM at Curtis Ridge. There were two others there and they had a NOAA radio. Wed AM the general area forecast was for 20% chance of occasional showers (not steady precip) beginning Thursday. No wind was forecast in the flatlands. An "uppper level disturbance," not a front was on the way. No mountain-specific information. The only current problem was, it was way too warm! We talked it over and decided to head up the Carbon but to keep an eye on things. (Seattle weather =/= Rainier weather) The group of 2 choose otherwise and headed out.
Wednesday morning we were at the base of Liberty Ridge (with a crashed helicopter and Tyler ??? and one other ranger there). The obvious, almost constant rockfall and recent injury turned us around before we headed up the ridge. Again, the current problem was it was too warm and sunny and the mountain wa falling at a good clip. The weather forecast from the rangers (whiteout and precip possible-probable but not certain Thurs-Fri) was an additional factor. Would we have backed off absent the rockfall? Maybe but it's hard to say - we did not have to make that decision. We would not have gone above Thumb given conditions Thurs AM, but the Alabama couple was already bivied in a crevasse by then. Had we climbed to Thumb Wednesday we would have faced a long wait or an unappealing retreat Thursday from the same location. And had we been in the field on the same schedule as the Alabama couple, I am confident we would have headed up from Thumb Rock Wed. AM as they did. Would we have been fast enough to make it down before the weather hit? Apparently one group was, but for us, ask me after next year when we come back to take another try at Liberty Ridge, a little earlier and with a lot of respect for the route. Then I'll tell you how long it will take to go up and over, except the conditions won't be the same. The ONLY thing we did different from them "before" is we had a 2-3 days extra fuel. So we would have had plenty of tea while battling up on top of the mountain.
Echoing what Mike said, I would not take potshots at decisions made by people who were in the field, (not at a desk), who had not the benefit of hindsight. A day or two earlier and it might have been the four of us taking a 3 day break in a crevasse in a storm. A thanks to those who are willing to bail us out when we guess wrong, as we all have more than once, is the only comment that need be made.