Not to beat this dead horse, but as a Marketing/PR guy my guess is that Eddy chose his words carefully.
"A new iOS 9 seed will support Apple Music"
"a new" : meaning you will need to update to another version different from that available, and not necessarily even beta3, just a new seed.
"will" : meaning at some point in the future, not the date specified (June 30).
I downgraded to 8.4 because I wanted Apple Music, and hated the battery issues with iOS 9 b1; would love to install b2 and teeter on doing it but I want to know for sure if it will mean missing Apple Music on day 1.
Cue has not responded to several follow ups asking for clarification if the seed will arrive on the 30th.