I can confirm I would not opt for that method, primarily as I dont know how to conduct such a ritual !!!
If I had no other choice in the whole planet then I would think I would opt for, whistle is in which hand tbh.
The issue I would have with it (and this is thinking about it far too much) is that rock, paper, scissors can be easily won by anyone with just a vague understanding of human psychology more often than not i.e. there's no chance involved in it as there is with a coin toss.