Famous actors should probably just steer clear of this subject and either let others make the case for them or let it die out.
On one hand, they have a point. Almost every industry has examples of family members getting career opportunities specifically because they are family members. Hollywood is certainly not unique in that regard. Plus, at least in Hollywood, you have to deliver to get another gig whereas in a lot of family businesses, a total deadbeat can collect a paycheck indefinitely because their family member boss will never fire them. You could argue Hollywood is more of a meritocracy in that way. Last but not least, isn’t it at least possible that the skills required to be a good actor are passed down from parent to child similar to how a great athletes tend to have athletic kids or a skilled tradesman teaches their kid the family business?
That being said, the public just isn’t going to be sympathetic to these arguments when they come from rich and famous people directly. If anything, it just gives the controversy more life, makes them seem out of touch, and fosters more resentment.