The buyer is likely Dongfeng Motor Company, a Chinese defense contractor.
Why, then is any Chinese car company in talks to take over Hummer?
Why is DongFeng likely the buyer?
Because of the Dongeng EQ 2050, which looks like this:

That's right, Dongfeng makes Hummer knock offs. And who's buying these knockoffs?
The People's Liberation Army, aka. the Chinese military.
That's right, GM is likely selling its Humvee division complete with the machines needed to produce the engines and chassis to a company that wants to supply the Chinese military with the model. (And it's not just the Chinese military buying them, Dongfeng has been selling military vehicles to the Sudanese government, where they are used in Darfur.)
Did they seriously think that no one would notice?