Why can't I access the Hermit's Lodge on Scylla for Vicar Max?
Solution 1:
There is no other way in, the door should become accessible whenever Vicar Max is in your party - regardless of other quest progression. However, the trigger that unlocks the door is bugged.
If (like me) you forgot to bring the Vicar with you the first time, then you probably fast travelled to the 'Abandoned Mining Outpost' with him, instead of walking all the way from the ship on foot again. When you fast travel there, the Hermit's Lodge door will remain in the 'Sealed' state for some reason.
Luckily, there's an easy workaround. After fast-travelling to the Outpost, leave on foot (down the road to the spot where some enemies spawn is probably far enough). After you've dealt with the enemies, double-back. The door should now be accessible.