I'd share the NAGC position statement with them and ask why they're going against the recommendations.

http://www.nagc.org/index.aspx?id=2455

Quote
In light of these circumstances, where comprehensive testing is available, NAGC recommends that WISC-IV Full Scale IQ scores not be required for admission to gifted programs. Instead, the following guidelines are suggested:

When the WISC-IV is used for the identification of gifted students, either the General Ability Index (GAI), which emphasizes reasoning ability, or the Full Scale IQ Score (FSIQ), should be acceptable for selection to gifted programs. The GAI should be derived using the table provided in the Harcourt Assessments website (Technical Report 4)[http://harcourtassessments.com/hai/Images/pdf/wisciv/WISCIVTechReport4.pdf]

The Verbal Comprehension Index (VCI) and the Perceptual Reasoning Index (PRI) are also independently appropriate for selection to programs for the gifted, especially for culturally diverse, bilingual, twice exceptional students or visual-spatial learners. It is important that a good match be made between the strengths of the child and the attributes of the program. Students who have special learning needs should be admitted to gifted programs, provided that there are other indications of giftedness and instructional modifications are made to fit the needs of the students.