Who is the contractor? The pump supplier or the piping stress engineer?

If the pump supplier gives it to you with higher factors there is no problem.

If the pipe stress engineer is asking for more allowable, this is the problem.

If the pump is not purchased and you are willing to pay more on higher allowable, yes you can and satisfy the pipe stress engineer. Otherwise the pipe stress engineer needs to provide the piping with more flexibility to satisfy the nozzle allowable, code and contract requirement.