I think it is safe to premise most recruiting posts as "there are exceptions"....but, from my experience the poster above is right on target. Hitting and offense is number one, can't be a liability at first base, but don't have to be a slick gold glove winner...just make the average players and hit, hit, hit. Every program I have been a part of has moved players from other positions that were "hot" at the plate, and some had never really played first base at all, and where given a crash course, in order to get them in the line up and move them over.
Bottom line, many of true first base signees have been moved to other positions, or replaced at first by others with better offensive capabilities....