Yes, it is available offline if you “Add to Apple Wallet”.
The ticket in Apple Wallet is still revocable if you transfer the ticket to someone else using Ticketmaster’s website, probably through an update that Ticketmaster pushes to the wallet [1].
Just recently dealt with this for a big Ticketmaster event. The Apple ID has to match the email address on the Ticketmaster account, or the ticket will show as Void in the Apple Wallet.
But it does solve the offline issue that the blog author was experiencing.
If it's a standard .pkpass, they could use it with an offline third-party app that can view those, e. g. PassAndroid [1]. Given Ticketmaster verifies Apple ID though, as mentioned in this thread, I'm not really sure it would work.
The ticket in Apple Wallet is still revocable if you transfer the ticket to someone else using Ticketmaster’s website, probably through an update that Ticketmaster pushes to the wallet [1].
[1]: https://developer.apple.com/library/archive/documentation/Us...