It is working very well and is very convenient to use since it returns the result of the hypothesis test, not just the test statistic. But: the alternative of S = 0 --> Z = 0 is not accounted for if I'm right.
For future updates I would also wish for a default significance level (for convenience). And perhaps a mention in the help text that there should be no autocorrelation in residuals.
Thank you for a nice implementation of Grubbs test! If I might suggest an improvement that would be to make the test work with other than vectors, e.g. to remove outliers from each row in a matrix separately