So the lower bounds you obtain this way are very poor. Indeed, if you look at both constraints for a variable x which is not exactly 0 or 1, but just fractional then we realise that both inequalities are redundant for most fractional values of x. So unless x is exactly equal to 0 or 1, we get a very poor lower bound and the solution is bound to be very bad. So, it is better not to use this trick. It is like not having precedence constraints at all.