There are at least two potential problems with adding F-35B to the carrier deck.
One is the effect of hot and high-velocity outwash on aircraft handling and operations near the landing spot. CV ops seem to make full-time use of all the available area, right to the edge of the landing zone.
The other is that the 550 foot (clean TOW) take-off roll of the B is longer than the cat stroke, which may mean that the JBDs are in the wrong place.