You can buy the map from Rusty even if you failed everything at the debris walker, nothing is soft locked.
When you first talk to the doctor, she will ask you to find a map, if you already have a map, you can just talk to her again and tell her you got the map. Again, nothing is soft locked. Here's the trigger for the dialog:
<<if $foundmap is 1 && $findmap is 1>>"[[I got the map]]."<</if>>
$foundmap is set to 1 once you get the map, $findmap is set to 1 after the first time you talked to her. It's two simple variables, as far as I can see, nothing can go wrong where you can't progress the game. Lore wise, you can take it as she is a fast talker and never lets you cut in to tell her you got the map already.