Not necessarily. CR varies among glow engines to their state of tune, and intended Nitro content, gasoline engines also vary in CR (mainly just their state of tune, but also a bit for intended Octane rating). Those ranges overlap widely, and only if you look at the averages, glow appears to have a slightly higher CR "in general". There are glow engines with CR 8:1 and there are gassers doing 12:1 or higher.
Nearly all glow engines CAN be operated on gasoline without modifications to CR, although sometimes on rare occasions it IS necessary.
Heck, I ran Rossi's on methanol and spark and had to reduce CR because they would continue running with a switched off ignition...
Nope... it does not work that way. CR is a geometric design parameter and an engine being worn does not lower its CR.
EDIT: going a bit deeper into that.
First, lets assume that an engine has a CR that would result in a theoretical compression pressure of 16 bar, but it is so worn out that at 1000 RPM only 8 bar is achieved.
That would mean that at 2000, when there is half the time availlable for leakage, allready compression end pressure would be 12 bar, at 4000 RPM there would be 14 bar, at 8000 RPM there would be 14 bar, etch etc etc.
So that does not work that way. (the numbers are not real, chosen for convenient calculating. The calculation is also not 100% correct, merely to demonstrate the idea).
second: the loss of piston seal means that hot combustion gasses are leaking between piston and liner, and this happens very violently. It damages the oil film and would, especially with gasoline (higher temperatures, less oil) lead to scuffing.
A worn engine is simply worn and needs new parts.

That is, apart from the CR discussion, certainly an option.

That never is a bad Idea, you never know what you can make out of it, and one mans trash is another mans treasure...