Considering the considerable effort that has gone into this by the time you are negotiating a contract, letting it fail over something that "is not important" and "is never enforced" would be very stupid of them.
So if they are unwilling to budge, that either means they were lying all along and the thing that's "never enforced" and is "not important" actually is very important to them and definitely will be enforced, or that they are a company that will enforce arbitrary and pointless rules on employees as long as they think they can.
Neither of which is a great advertisement for the company as an employer.
Most of the time is basically just FUD, to coerce people into following the rule-that-is-never-enforced
Do not sign a contract unless you are willing to entirely submit to everything in it that is legally binding.
Also be careful with extremely vague contracts. My employment contract was basically "You will do whatever we need you to do" and surprise surprise, unpaid overtime is expected.