The landlord set the pace not the applicant and if they can not comply you reject their application.

Also, you should mark down the reason for your rejection in case an applicant files a complaint against you.

So I am trying to determine if it's still legal to automatically reject lawyers and law students on that basis alone?  

You process in order of receipt and accept or reject an application before processing the next one. 

Even if you reject Section 8, if you are in low income, you will get applicants and tenants who don't take care of things and who do not get their income stream from a traditional job (and avoiding those situations is discriminatory).  

Here in Texas landlords are required to disclose tenant screening criteria as well as reasons why an applicant may be declined before the applicant pays the application fee.The rejected applicant has the right to demand a refund of the application fee if they are rejected and the screening criteria were not disclosed at the time of the application.

This is an easy rejection.  

The nuances of friends-as-tenants will make it difficult to enforce your business policies, even if everything is clearly contracted.One trick was knowing what to say -- how do you even reject a friend's request to rent without messing up the friendship?

For example saying to look at a tenants car condition for an indication of cleanliness but later saying that you should clearly let an applicant know why they were rejected (would you tell them it's because their car was dirty)?

I truly believe he is just trying to make her life hard because she rejected him.