You can say whatever you want about other patents. It might not be sensible for various reasons, but no one will stop you.
However, a patent must also set out the best mode of performing the invention. If it fails to do so, the patent is invalid.
However, best mode is pretty broad. It doesn't just mean highest performing. A cheapest, but lower performing option can be the best mode if you are looking for economy. A safer, but lower performing option can be the best mode if you are looking for safety. An inferior alternative can be the best mode, if you are looking for alternatives. Basically anything can be the best mode under the right lens.
In this case, US5069827 discusses FR2553560, and notes certain problems in it. These problems seem reasonable at first blush. US5069827 also presents a solution that ostensibly doesn't have those problems. So it seems they have disclosed the best mode of performing their invention. This is the case even if FR2553560 discloses a better invention (for some meaning of better).