The problem with this theory is that in any listening environment, except for something like an anechoic chamber, the decay time will be dominated by the room. So if this is the explanation, some pieces of the explanation are missing.
This is not correct. How a woofer stops depends on its damping factor. The damping factor depends on the design of the driver and enclosure. You can find sealed speakers with poor damping and ported speakers with excellent damping.
