What is the standard of measure for DFR? If you have any legal perspective at all you will realize LUP is NOT a standard. "Legitimate" is an adjective of conclusion, a judgement if you will.
First you must have a date of ripeness to even have a trial and then and only then a proposed or alledged purpose might be judged according a standard or range of reasonableness.... But more than likely it is not "purpose" that is judged but rather it is "product"...
10 points if you can cite the standard of legitimate union product, and another 10 points if you can cite the authority that most recently repeated that standard... of a wide range of reasonableness.
1,000 points if you can show a "standard for purpose" .. Ha!