Definately agree, she needs an advocate with her. A lot of schools don't like to do them, because it is extra paperwork and they are "required" to do everything in the 504 plan and be held accountable for it. They would much rather do a "friendly" agreement, save the paperwork, and then when they refuse to follow through there is nothing that can be done by the parents/guardians of the child.
Another thing your friend might want to look into is having him tested for "gifted". My friend's daughter is "visually" gifted and like your friend's son, does much better when things are shown to her visually rather than verbally. She also tests better when the test is on certain colors of paper vs being on white paper with black letters.
Those types of accomodations can be added into the 504...I think the teacher/school is reluctant because the teacher is a "verbal" person, and she would have to completely change how she teaches to accomodate your friend's son. Something, if she is been around for a while, she is not going to want to do and can with a "friendly agreement" just pass it off with a 1/2 hearted attempt or not even attempting, and there is nothing anyone can do. It may also mean getting special books for him, etc. For instance, if he is a visual learning, and if his reading is better when things are printed on yellow paper, then they will have to get everything put on yellow paper (tests, homework, etc)..again extra work and possible extra costs to the school.
If it gets put into a 504, then she is required to do it, or they are required to move him into a classroom or put an instructor in who will/can meet his needs.
Have your friend go to the public library and request copies of the Education Publications by Wrights Law. They are listed on their website.
And again, I would even consider asking him to be tested for giftedness. He may do exceedingly well in all but the one area. She may also want to look into a good psychologist who can do IQ and giftedness testing to determine what works best for him....