You indicate "they took off the common tie." If this is a multi-pole breaker taking off the common tie does in fact violate NEC rules. That means that 1 of the poles can trip leaving the other pole(s) live. No a good situation.
While I agree taking the factory installed handle is a violation I do not agree with the rest of your statement.
A "Common Trip Breaker" will trip all poles on a short or overload regardless of the handles. A "Common trip Breaker" has an internal mechanism to make sure of that.
The only thing that handle ties ever guarantee is the opening or closing of all poles when switched by hand.