It sounds like they were given good advice on doing the recover. But the possibility that another user might have one of the records open for editing shouldn't result in a crash. That will "edit lock" a record and you'll get an error message that a record could not be updated, but it should not produce this crash.
Best guess is that the file is damaged in some way that either the recover cannot fully repair, or some issue that originally damaged the file damaged it again at some point after the recover fixed it.
Things to keep in mind about Recover:
While Recover almost always detects and fully corrects any problems with your file...
- The recovered copy may behave differently even if recover reports "no problems found".
- Recover does not detect all problems
- Recover doesn't always fix all problems correctly
- Best Practice is to never put a recovered copy back into regular use or development. Instead, replace the damaged file with an undamaged back up copy if this is at all possible. You may have to save a clone of the back up copy and import all data from your recovered copy to get a working copy with the most up to date information possible.
And here's a knowledgebase article that you may find useful: What to do when your file is corrupt (KB5421).