Hard to say without details; but now that the weakness is known it may become a lot easier. It's one thing if you
think it
may work if you have the correct parameters but aren't sure, and quite another if you
know it
will work.
Password managers are kind of a "defence in depth" thing; practical speaking, a passwords.txt opened with notepad is probably fine for many people. No one is in your computer checking your files. You have a password manager for when that does happen, just in case. And usually this tends to be a targetted attack, which can range from some country's secret service to a jealous spouse to a trolling sibling. If that extra protection is ineffective ... yeah, that's not great.
This really is "better safe than sorry" type territory. Password managers (including Roboform) already do this by notifying users a password may be insecure after a leak. A lot of the time that's not really needed if your password is sufficiently secure, but "better safe than sorry". This is not all that different.