It seems like it would be super easy for them to close this loophole. If you use the model that free tier listeners (real ones) will listen to about the same distribution of songs as the paying listeners, then just stop counting all free tier listeners and multiply the amount paid out for the pay-tier listeners by an appropriate factor to make payouts the same as before.
Did he actually do that? He said he was going to, but Leon Musk is famously a big fucking liar.