No, you got it right . March 24th patch changed that. Along with almost every other single-shot boss.
The following bosses will now respawn when a player exits and re-enters a map:
Tiny Destroyer, Boomer, Rabid Adams, Giant Shuggarath, Bruce, Rooster Booster,
Even-More-Disgusting Tork, Drongo Bones, Meg, CLAP-L3K, Lost Legion Powersuit Noob,
(Note: Col. Zarpedon's loot pool has been added to the Sentinel since Zarpedon