Although the NAIA only has about 250-300 members and its members tend to be small private schools. FWIW the comparison between NAIA and the NCAA is probably like this:

NAIA DI = NCAA DII
NAIA DII = NCAA DIII

Also, it appears the NAIA only has 4 members with over 10K students and 148 members with 1,001-9,999 students

University of British Columbia = 44,000
University of Victoria = 20,199
Keiser University = 16,333
Georgia Gwinnett College = 12,500

It may come down to how much do the large/medium G5 public schools have in common with small private schools (aka NAIA members). I guess it is even possible that the G5 private schools don't have that much in common with the NAIA members. It is possible that a conference like the Patriot League and Ivy League (ignoring the academic side) may see no/minimal difference between the NCAA and NAIA.