It depends on the type of game. Some games people expect to play with a mouse, while others are played with a controller and/or keyboard. If your game is one that people expect to play with a mouse, then disabling it will likely negatively impact your game's reception.
However, if your game is the type where people typically use a keyboard or gamepad, disabling the mouse shouldn't be a problem.
That said, based on your description, I agree with @redonihunter: disabling the mouse should be a design decision, not a patch to fix a bug.
Your problem is that the character needs to interact, not the cursor. You have two solutions: check the cursor's position relative to the character. If it's over the character, the click counts as an "action"; if it's far away, it counts as a "movement."
Another solution is to leave the mouse code as is and add a condition when the "action" is executed, requiring the character's position to be over or near the object attempting the action.