Who Built the Moon (alternative ideas)

Geologic study of moon rocks returned to earth by the Apollo missions.

Demonstrated relative densities of the 4 terrestrial planets and the moon.
Mercury’s average density of 5440 kg/m3) is much higher than the Moon's 3340 kg/m3) and is more similar to that of Earth at 5520 kg/m3).

However, adjusting these average densities for the pressures due to overburden pressure, we get even more contrast.

Planet

Mercury
Measured Density 5440
“Uncompressed” Density (kg/m3) 5300

Venus
M 5300
U 4400

Earth
M 5520
U 4500

Moon
M 3340
U 3300

Mars
M 3940
U 3800

web.ics.purdue.edu...

What I would like to know is why Sean Soloman, one of the Scientist that ran the Moon quake experiments would find it so frightening if the Moon is found to be hollow.

Experiments have shown the Moon is hollow.
In 1969 NASA hit the Moon with a lunar module in an impact that generated the equivalent in energy of about 1 ton TNT. Of this event, Maurice Ewing, the co-director of the lunar seismic experiment, said "it is as though someone had struck a bell, say, in the belfry of a church, a single blow and found that the reverberation from it continued for 30 minutes." On a later mission NASA repeated the experiment, this time with the equivalent of 11 tons TNT. This time the Moon shook for 3 hours 20 minutes and enabled them to learn something else: according to one NASA source, the Moon "wobbled" in such a precise way that it was "almost as though it had gigantic hydraulic damper struts inside it". At the time, Sean C. Soloman. MIT said experiments had suggested the "frightening possibility that the Moon might be hollow."