nzo new high, page-15

please explain why it is their best interests to do so?
Know doubt you are refering to dilution.
As a heads holder that isn't selling shares it may be in your best interest if people dump stock to keep the heads out of the money (although this is based on a dubious belief that dilution will see a reduction in the share price and therefore a reduction in market cap)however it certainly isn't in the interest of major holders to dump stock.
That would be cutting off their nose to spite their face if they believe the price will rise.

Unless of course you are talking about dumping stock to buy back cheaper which of course is market manipulation and no large holder would risk it.

The value of a company is not simply it's market cap and to assume that exercised options does not add value to the company is perhaps not correct. I believe cash at hand is one of the considerations when valuing a business?

Sure there is a cost with more shares on the register however there is a cost to the company in all endeavours to secure income isn't there?