If you are professional you know what kind of potential problems might happen and you know what are reasonable possible approaches to handle it.
If security of your piece of software relies on default values of some settings I would reasonably expect you to have automated tests to verify that these settings have correct values.
Next time you hire an electrician who causes damage to your house because he did not follow procedure to wire it correctly, will you be still calling him "professional" because he quickly removed the short?
Yes -- it is important how you rectify those mistakes.
But being quick at rectifying mistakes does not yet make your actions professional.
But if you are calling somebody or something "professional" what you are saying is they act as if they were doing it in a certain way. If they don't follow the practices it does not matter if they are doing it for free.
It is like saying a kid is doing something professionally (even if he is not) and argumenting that it is because he isn't paid for it.
I mean I fail to understand what are you trying to say, someone stops being a professional as soon as it hasn't covered a test case?
Or are they kids just for having slipped a bug? Despite their work powers a lot of companies software (including the ones I work for)
Are you just trolling?
I don't know if they are or are not professionals.
It is just my opinion that being nice and prompt about removing cause of the damage after they have caused damage through recklessly ignoring industry standards cannot be reason to call their entire set of actions around this particular issue as "professional".
If you consider that kind of behavior recklessly unprofessional I'd be amazed to see the kind of tests you write for your code.
So they didn't say their "entire set of actions" was "professional" just that it was disclosed and resolved professionally.