We could only know this if we had access to the articles of association or the terms of the sale. However, none of that will relate to percentages. If SD wanted to retain voting rights on certain issues, he could write that into the terms of the sale, by saying the owner of 1 share allows that right.
I don't get why SD would sell a large % of the club to KLD to then go on to block further investment, it makes no sense at all. As per the first sentence, and as you pointed out if he wanted a veto on certain items he can have that regardless of % and it was him that sold on his terms.
The basis of the conspiracy theory seems to be that SD will try to hold us back or to block KLD investing, but if that was true, why would he sell to KLD in the first place. Both KLD and SD were happy to sign the deal only a few months ago, they obviously both see it as beneficial.
I think the fans are blinded by the state of the football and league position, that SD/CM are only ever seen as bogey men now. I'll be honest, they've got a lot wrong, but I don't think it was done deliberately. I'm also sure they wanted to make a profit in the process, but so do most businessmen. We've got used to Short pumping in millions of his own cash every year and want that to continue, but it didn't and there wasn't another billionaire happy to take over. So now we're in the real world, where we have to live from our income.
I agree with your comment that there isn't a valid argument for secrecy, but we don't know who and why that NDA is in place. It could be for reasons we don't expect. But, the point remains, it makes no difference if KLD has 60% or 72%.