This announcement seems to coincide with the signing of Buakaw Banchamek by K-1 and serves more as a "see, we have some big stars" than an actual signing, as Andy Souwer was originally announced for the event. Andy Souwer was originally announced for the September 14th event in Mallorca, Spain, but then again, so was Mike Zambidis, whom we've heard might not be participating in the event after all.
That being said, the idea of Andy Souwer and Buakaw Banchamek stepping into the ring again is an awesome selling point for K-1's upcoming World MAX Final 16 and World MAX tournament as a whole. We've also heard that there might be some other surprises, but nothing is set in stone yet. The final card should be available within a few weeks now and will be packing a decent amount of star power to go along with talent, which is the important thing here. The addition of Henri Van Opstal is also a good choice as Van Opstal has been tearing up Shoot Boxing of late, even meeting Souwer in the Finals of the 2012 S-Cup.