Luffy was similar to any other early possessor of that DF who couldn't reach to the limit to awaken it. So WG didn't bother to capture Luffy or his DF.
And would you explain what are the ways WG can take control of DF ? Only Blackbeard has shown it.
When DF user dies, DF appears somewhere in the world. No one knows it unless someone eats and shows its powers.
Now whats the point of Talking about awakening now ?
I feel in intensive use of DF ability and fight, one may be able to awaken it's DF.
And of course this fight is World class fight so WG is worried about awakening and gave order to eliminate Luffy.