In their study, Bliese et al. (2017) argued that mixed-effects models are appropriate even when ICC values associated with the outcome data are small and non-significant.

I usually use this reference to justify using GLMM with low ICCs.

Best regards,

Angel.

Bliese, P. D., Maltarich, M. A., & Hendricks, J. L. (2017). Back to basics with mixed-effects models: Nine take-away points. Journal of Business and Psychology, 33(1), 1–23. doi:10.1007/s10869-017-9491-z 

Thank you!