Delta wing fighters don't really have a conventional "stall". They just get progressively harder to fly and require more and more power to stay airborne as they slow down. The f-16 computer keeps it from getting too close to a true stall, and the f-15 controls typically can't force a high enough angle of attack to lose all lift as in a conventional stall.
I suppose 150 is a reasonable enough number as a practical minimum for an F-15, as below that speed a mistake could result in significant altitude loss.