I'm no lawyer but I would imagine your friend would have to be able to provide evidence that people of the opposite gender had access to things they didn't or they benefited in some way because of their gender alone.
You stated your friend: "had to deal with management that wouldn't address (logistical problems) and hindered business."
Since you did not address what those "logistical problems" were it's difficult to know if (gender) had anything to do with it or if your friend was asking for "special treatment" which would have discriminated other employees and gave her or him an advantage.
Generally speaking companies are looking to hire candidates who will "fit into" their operations and not someone who insists they make exceptions for them or change how they do things in order to accommodate them.
A lot of companies actually have employees sign a document that states they're physically or mentally capable of doing the job "as described".
However as I stated earlier the key is providing evidence that the opposite gender was treated better. Naturally if there is another person of your friend's gender who is an existing or past employee who suffered from or observed the same treatment it will bolster their case. On the other hand if there are employees of the same gender who are happy with the company it will be tough to show there is a gender bias.
Most companies these days craft a "paper trail" before actually firing anyone. They usually can point to "performance reviews", "verbal warnings", and "written warnings" they've had the employee sign/agree to over a period of time.
Once a company puts an employee on a "developmental plan" rarely do they plan to hold onto him or her. They simply wanted to build a "paper trail" in the event they get sued. If your friend truly feels it was systematic gender discrimination they should probably speak with an attorney to determine if they have a case.