why Kimo instead of Tank vs Ken?

Kimo will be a better match. Who is still interested in tank after his last 3 performances especially considering he costs $150,000

I'd rather see this than Tank. Tank is 0-3 as of late and Kimo made him look REALLY bad.
Kimo might not exactly be Rickson, but he's certainly a decent grappler.
I think this is a good choice for a fight because Kimo and Ken can both strike adequately and have some ground skills. The fight could end any number of ways.

Ironically both guys have had some of the most boring fights of ALL TIME with none other than Dan Severn.

this is fuckin bullshit.i wanted to see some more bad blood get settled in the octagon.

Tank vs. Ken is something I would much rahther see than ken vs. Kimo, but it could still be a decent match. I hope that it isn't the main event, though. That would be pretty weak.

Ken vs Kimo might be a more interestng fight to watch but Tank vs. Ken had at least the potential to be interesting and it is so much more hype-worthy...  its a shame b/c I was finally coming around to wanting to watch Tank vs. Shamrock...