FOZ, do you know which version of the test he took (2-5 v. 6+)?
Is he feeling challenged in school? Does your school provide an average RIT and range for the GT math class he is in? How does his teacher feel that he fits into class? You certainly don't need to answer all of the questions here, but the answers will probably give you an indication as to whether you need to have more discussions with his school about placement.
I do not think that the MAP test is meaningless at all, but I would use it in combination with this other data, to better understand whether he currently has a good placement. Depending on his school, you may still find that his scores are very, very high.