Unsafe
My understanding of how the blacklist is compiled is simple: The airlines listed have been found to have serious mechanical or other defects making it illegal for them to enter French airspace.
In my experience, having dealt with (formerly UK blacklisted) Sierra Leone registered airlines, the airline will only be placed on the blacklist if the causes of the defects found (such as shoddy maintenance) are not rectified immediately, or if defects are more than an incidental occurrence.
In my opinion, the blacklist does not tell the traveller anything about the safety of other airlines. Not being on the list is not a 'seal of approval'.