If you would like to always use the batch stats, you can just disable the running stats with track_running_stats=False.
It won’t be cheating, but there might be some shortcomings.
Using another batch size in the test case as in training might lead to worse accuracy.
If your batch size is > 1, your output won’t be deterministic, since the prediction of one sample depend on the batch it is predicted with. Shuffling the test set and predicting it again, might also lead to another accuracy.
If you can handle these effects or they won’t occur, because your batch size is 1, I wounldn’t see it as cheating.