Just my thoughts

This is interesting, I understand the teacher's issue, but her solution is worse then the problem of some kids trying to read above their level.

Instead of keeping the harder books away until the reading levels can be determined more levels need to be kept out until levels can be determined. However, this could be more difficult for the teacher to deal with until evaluations are complete. This difficulty may encourage the evaluations to be completed quicker. The teacher is answering the following question, whats worse having readers attempting (with out much success) to read above their levels, or to have readers being bored (and discouraged) reading well below their reading levels. Also, it is absolutely ridiculous for the teacher not to allow you dc to bring in a book. I would feel that she does not value my understanding of my own child's reading level.

Please post after your meeting I am, as I'm sure others are also, curious about what they could possibly say to defend this teacher's decision.