Q. In Exodus 24:9-18 (KJV) Moses, Aaron, Nadab, & Abihu & 70 elders went up (v10) and they saw the God of Israel; (v11) also they saw God, and did eat & drink. Was God holding back His glory so as not to hurt these leaders?
A. In Exodus 24:1-2 God told Moses to come up on the mountain with Aaron, Nadab, Abihu and the 70 elders. He said only Moses could come near. The others had to remain at a distance. According to Exodus 24:9-11 they were able to see God from a distance, but He did not raise His hand against them.
You have to read it very carefully to see this, but I believe Exodus 24:12-18 refers to a different event, the one where Moses went up the mountain to receive the stone tablets of the Law with instructions on building the tabernacle and establishing the Levitical priesthood. That time Moses stayed on the mountain for 40 days and 40 nights while the elders remained below with the people.
What makes me believe this is before the first visit God told Moses none of the people were allowed to come up the mountain (Exodus 24:2) and before leaving on the second visit Moses told the elders to refer any disputes the people had to Aaron and Hur who were with them (Exodus 24:12-14). This tells me all the elders remained below with the people when Moses went up for the tablets of the Law.