While it *could* be done.. it'd be much much tougher to keep something like this seriously quiet in this day and age.
I'm not trying to say that they
are doing this, but just engaging in speculation for the entertainment value.
Let's say, for the sake of argument, that Disney is considering building a theme park/complex in Texas. The first step would be ensuring that they could secure the land. Well, there's a noncommittal way of doing that, just as you mention -- buy up land to use as warehouses, etc. A legitimate business purpose, and recorded as such in financial documents.
If and when enough land has been purchased to make the project possible, and capital concerns are in place to actually do the project, then the rest of the package (zoning, etc.) can be done. At that time, the re-purposing of the property becomes a material issue and needs disclosed. Any off-the-record talks before then with local politicians to gauge possible support or opposition isn't necessarily material, because it is simply Disney looking at options, without making any financial commitment. Leaks of such talks can be pooh-poohed as idle rumor-mongering... after all, it's just land purchased for warehouses (or whatever).
Of course, I don't believe a word of it. It's a huge capital investment to make, and I don't think the current economic climate justifies it. While such a location would be geographically distant from DL and WDW, one can see from current specials that Disney is pushing hard to boost attendance at WDW -- competing with themselves doesn't seem to be a particularly wise idea.
One thing a Texas location could have in its favor, however (akin to the debunked rumors of a Williamsburg, VA location), would be a theme park location with easy access to a potential port of call or embarkation/debarkation point for
DCL.