Bert, please assume that everything below is hypothetical, but based on a letter similar to the one I received.
I understand what you're saying. If a site owner thought that there was the possibility of confusion, it might be remediated in the way you describe.
However, if the letter doesn't demand that the site owner remediate, but rather demands the owner stop using the domain and deregister it, then putting a disclaimer at the top doesn't satisfy the demands of the C&D letter. Since legal action is threatened with respect to ownership and maintenance of the domain, the threat of that legal action would still exist even after the remediation had occurred.
Moreover, what if the site owner thought that there was no need for any remediation whatsoever -- that, say, the letter was either thuggish foolishness or foolish thuggery? Then it might be bad to take this putatively remedial step: After all, if the page owner did something to mitigate the town's complaint, that might be taken as a sign that he thinks the town has a point. Then, if the town is merely being foolish, they could claim that they were right all along and that the site owner should comply with the rest of the demands of the letter; and if the town is being thuggish, they could continue to thuggishly demand that the site owner comply with the rest of the demands of the letter. Either way, unneeded remediation seems to be a losing move for the site owner.
Therefore, if the page owner doesn't think the town has a point, he shouldn't comply at all while this threat is looming over him. Only when the town has written a formal retraction of its demands should the site owner make concessions (if he wants to), whether they are really needed to avoid confusion or whether they are provided for the sake of "getting along".
Does that make more sense?