I finally ended up calling them today after debating whether or not I was going to send my app in, as I also don't have the non-science letter, but have the rest of the letters. I asked straight up if missing the letter would break my application, and he said that it shouldn't. He also said that he's been getting a lot of calls about non-trads and non-science faculty letters, so I wouldn't be surprised if a lot of applicants don't have that requirement. I just hope that it wasn't a money grab, and now they'll just screen us all out