Does Destiny 2 have a free trial?
Bungie has announced a free-to-play version of Destiny 2:
Destiny 2: New Light launches October 1, 2019 and is free to play on every supported platform.
There was a free trial weekend, there is not (as of this answer) a permanent free trial.
The SAXOPHONE error help page on Bungie.net (That you linked to) makes this very clear.
Players do not own Destiny 2, but have it installed from a Free Trial weekend and are attempting to launch outside of a promotional window.
On top of that, Activision and Blizzard Entertainment are still separately run Business Units underneath the wider Activision Blizzard entity. Calling Destiny 2 a "Blizzard" game, is not technically correct as Blizzard Entertainment (the game development company), had nothing to do with the development of Destiny 2, besides allowing Activision to use their Battle.Net content delivery platform.