Employer might be worried that you won't be motivated to deal with the bullshit that comes with the job either. More likely they just don't give a shit though
There's a few types of bullshit when it comes to employment. It's either necessary, in which case I will deal with it, or it's not, in which case I will find a way to either not (have to) do it, or spend as little effort as humanly possible on it.
Making up bullshit cover letter requirements is squarely in the latter camp so noooo thank you. If an employer is going to START with requiring bullshit I'll be glad to dodge that bullet.