Carbon fibre reinforced composites do not need to see a flame to experience degradation, just elevated temperature.
The carbon fibres themselves will start to degrade at around 400 degrees, the resin in these forks probably much sooner.
The fact that there is some visible trace of the fire on these forks strongly suggests that they are fu*ked. Using them in my opinion would be extremely risky.
The metallic parts on these forks may also have experienced changes due to their exposure to heat that could adversely affect their structural integrity.
My opinion is that you probably should not sell these forks to some unsuspecting individual, and probably better to take them out of circulation.