They already built it. It's operational. I know the planners thought all this out when doing so. Two vessels means the difference in potentially having a capability when you really need it and not having it. So, yes, if they sell one of the two they have...I'd call it short sighted.Short sighted? Finance, Manpower will be the key for French whether they can afford a 2 or 1.
Now, if they license build a new one for the Russians which they then sell...that would bring extra money in. Be good for France, and once they started license building their own, good for Russia too. Or if they use the dollars gained from this sell and build a second one for themselves...that's the same benefit.
Now, if the idea all along was to really build a demonstrator that they could then market...then that's another matter entirely. But I do not believe that was the idea when building the Mistrals.