Great question. Before I can answer you should know that I am biased toward .tv and .com.
.Com only because it was first and .tv because of the inherent branding advantage the extension has over all others in the video age we live. However, it is still a speculator's game until every person can name one .tv site without thinking.
The first question you should ask yourself is what do you define as a keyword. Keywords mean different things to people. For example, is it a keyword because it sounds brandable or is it a keyword someone would naturally type into their browser looking for some .info site.
Personally, I have never typed a .info site into a browser, but hundreds if not thousands of .tv and .com sites.
If these domains are keywords and they are available, then you should be asking why. Without seeing the names, I cannot tell you whether the previous domainers that came before you simply missed them, or whether they passed them up, or simply never thought of them (either because they aren't keywords or the .info extension has not fallen into mainstream demand as have other extensions).
The one thing I liked about the reply from the previous poster is that he noted that .info names are cheap.
My advice is to be a little clever. Setup a domain parking account if you don't have one. Sedo or parked.com will work. Determine what you need to setup the DNS for the new names to populate using their templates. Then find a registrar like Moniker that allows for bulk registering and domain tasting.
Moniker provides discounts on names to namepros members. I would setup an account and in the admin panel, specify that all domains registered should use the DNS of your parking company. Then use the bulk register feature to register all of your .info names.
Meanwhile, post the names in the appraisals thread immediately after you register them. For the next few days, read the replies to those threads and watch the type in traffic. Hopefully nobody that you request an appraisal from will visit those sites so you can accurately gauge normal/natural traffic patterns. If within the registrar's domain tasting period, you don't like what you hear or see, then you can return the names and get your money back.
Before you register them, you also might want to think how you can monetize them to capitalize on their keyword status. Hopefully your words receive high results in google and overture. That is one measure that domainers use to evaluate keyword acquisitions.
I would love to help out. PM me when you post the appraisal requests and I would be happy to chime in again.