Armstrong & Aldrin landed with only 30 seconds of fuel remaining before mandatory abort?

They would have run out of the fuel needed for a safe landing, would have had to drop the descent stage and fire the ascent rocket, returning to the 50,000 foot altitude. This would have created problems as the CSM in which they were to return to Earth (and which had Collins aboard) would have been in a very different part of its orbit, not positioned for a rendezvous. It would have taken several hours of tricky maneuvering to bring the ships together.