I have to admit that there is a need for high allowable on nozzles in case there is no space for flexibility and the pipe size is large (too rigid to lower nozzle loading in short distance). But all the options need to be exhausted.

If this is the scenario they need to approach your company officially and explaining all the reasons that they cannot manage. So they need to convince the owner management instead of pushing the engineers to accept what they need.

In the Middle East the contracting approach seems to me too difficult to manage since there is no FEED study to see all the problems earlier. So all the problems need to be solved by owners engineer somehow when the problem arises.

If this is the scenario I would ask the contractor to approach the owner management, or let the management know what is happening in writing, ask their approval on the issue.