Yes, Umarov is a terrorist, but he has power and has proven to be a much-feared leader. Quoting him is just good journalism and has nothing to do with being his servant. As for Ramzan Kadyrov, he and the 5.000 Kadyrovtsy armed men, manage to kill and torture more than Umarov. Russia's Putin of course is Kadyrov's protector, while honest journalists like Anna Politkovskaya - who knew and wrote about the murderous Kadyrov clan, are murdered. 

to fight for his country. 

The phenomenon of terrorism exists only because of the media.
When a "journalist" publishes words of a terrorist he encourages the terrorist to kill more to attract more attention of the media. Without media the terrorist would be just an unknown bandit.
Dear JohnN,
if you have evidence about Anna Politkovskaya case, please bring them to the international court. Or you just quoting rumors?!

Journalists have a lot of accidents

Umarov called off attacks on Russian civilians, that is what Western media has reported and that is what I have read. In short, Umarov considers the enemy of his enemy his friend and that the current events in Russia against Putin are a sign that Putin is no longer supported. Logic would indicate that the "war" against Chechnya sponsored by Putin and FSB, and since Putin is under scrutiny and so are his actions including the Chechen war.
As for the US not doing anything about Umarov, I cannot comment because there is not much information out there, but it would seem from this article that Russia wants the US to do something about it. What is the US going to do? Launch an incursion against the rebel fighters within the Russian borders? It took the US 10 years to kill bin Laden, Umarov is less of a priority and has no established links to Al-Qaeda so he is no concern to the US.
The Russians should have found Umarov already. 

Umarov is a monster and should be brought to justice. The US putting Umarov on a list will not do anything. It just shows that the US has recognized him as a terrorist and has given the US the power to freeze his assets, prevent money flows, and to prosecute him for terrorist activities. I don't know how the US will accomplish such tasks.
Katya: Apparently on March 10, 2011 the UNSC Sanctions Committee on Al-Qaida and Taliban added Umarov to a list of individuals associated with Al-Qaida (from Umarov's Wikipedia page).