How can I remove negators: potential shouldn't be so ‘fanciful or remote’ that the proferens can't be supposed to desire protection from it?

If “fanciful or remote” are undesired characteristics, first state the preferred situation which assumes that they are not present, and then add them back. You can do that using unless.

The proferens may be supposed to desire protection from the potential for non-negligence liability unless that potential is fanciful or remote.

Although the repeated that potential here could simply be it, that might be ambiguous and restating the noun itself is certainly clearer.

However, rewording the sentence changes the emphasis. In this version, we look at things from the proferens’ point of view; in the original, it considers the potential for liability.