If a contractor installed exactly what he asked for, an RJ45 jack which would be unusable for his needs he would have no grounds to stand on to demand it be corrected without paying more. By specifying the technically correct name as well as the colloquially recognized name he is being precise and accommodating.

If a contract requires RJ45 terminated Ethernet patch cables and the contractor delivers keyed RJ45, they have not delivered because RJ45 doesn’t even have the correct conductor layout to act as an Ethernet cable. Contracts call for RJ45 all the time and there are no mixups. You’d probably find it quite difficult to even find vendors for keyed RJ45

I know this feels like a technically correct gotcha, but in fact is not. Do some parametric searches on digikey and flip through some manufacturer catalogs. If you go out of your way to misinterpret industry standard jargon you won't be paid for your work and you'll lose the contract.