This is not correct, Regal has ISX in its other fund(s)
ie in Regal Long Short Australian Equity Fund. I agree with your thoughts though, that it could be because ISX was entering the 300, so that it needed to exit from its Emerging Companies fund
https://www.********.au/2019/03/01/top-fund-manager-reveals-4-asx-tech-shares-to-buy-in-2019/