YES

1 decompositions
 #0 -----------
   1: or(x,T()) -> T()
   2: or(x,F()) -> x
   3: or(or(x,y),z) -> or(x,or(y,z))
   4: or(x,y) -> or(y,x)

@Jouannaud and Kirchner's criterion
--- R
   1: or(x,T()) -> T()
   2: or(x,F()) -> x
   3: or(or(x,y),z) -> or(x,or(y,z))
   4: or(x,y) -> or(y,x)

--- S
   1: or(x,T()) -> T()
   2: or(x,F()) -> x
   3: or(or(x,y),z) -> or(x,or(y,z))
   4: or(x,y) -> or(y,x)