"As part of our Patent Acquisition Agreement (see section 4.4), sellers will retain a license back to their patent. For you lawyers out there, the license is “irrevocable, nonexclusive, nontransferable, nonassignable (including by operation of law or otherwise), nonsublicensable, worldwide, [and] fully paidup.”
That does no one any good except the seller. For any seller, this kind of thing is table-stakes (no one wants to sell someone a gun pointed at their head).
But if the seller is specifically concerned about their patent being used offensively on others (which I suspect was the original commenter's concern), then this provision is useless.
I think I am misunderstanding you. If they give much more, Google might as well just pay one to void their patent instead of assuming ownership.