You're probably right, but some companies have it written in their by-laws, that their shareholder books are open to anyone who cares to visit their business office.
To me, it's a question of honorable service. What do they have to hide? In most cases, it's just going to be a list of brokerage houses, because most shares are held in "street name" these days.
If a big holder wants to protect his name, his simply leaves the shares deposited at his broker. No big deal.
It's really hard to trust Wall Street when the CEO's don't want the names of brokerages released. Obviously, the brokerages would understand which information to pass on to the holders, and which is simply pestering and irritating.