I'd be interested to see a definition of "the problem that doesn't really exist". It sounds like a "Straw Man" which works only because it's undefined.
CaRT's objectives are obvious, and don't need to be justified by a major problem: they want to be able to control the amount of time boats are allowed to moor at different places.
Among other things they clearly want to:
Stop any one boat occupying any towpath mooring longer than 14 days except by permission from CaRT
Provide "visitor moorings" that may not be occupied by any one boat for more than a specified time that's less than 14 days
Allow boats to moor in one place for longer than 14 days under appropriate circumstances (such as during the winter)
There's no point in arguing that these are "bad objectives". They are clearly intended to ensure that moorings are shared fairly between all boaters. There are clearly places and time periods where demand for moorings exceeds supply, and a means to share the scare resource (mooring spots) is good for boaters as a group ... but less convenient for individuals who don't want to share.
Naturally there's nothing wrong with interpreting the law in a way that doesn't support these objectives. It's certainly open to different interpretations, and the "official" meaning and scope can only be established in court.
On the other hand all the claims that "there is no problem", and implications that CaRT is acting in bad faith make no sense. They're looking for ways to share access to a scarce resource by some other means than "first in place has an unlimited right to occupancy". Their means may or may not be in accordance with the 1995 act, but their objectives are definitely reasonable.