I don´t think its about Greenland, but I could be wrong. Its properly more about a trusted ally, that has the capability. But they could also have choosen the French CMA CGM group ( but Denmark is properly a better trading partner then the stubborn French, since they don´t have nukes )
Well heck we both could be wrong

.
But it’s reasonable that one or more of all of our points are being factored in.
What stands out in both is that nations rarely make long term economic decisions based solely on diplomatic affronts, real or perceived.
There is always the opportunity in the global economic and trade world for everyone involved including China and the US to move towards a more open trading system.
When trade issues are raised diplomatically and ignored or dismissed the first reaction is not to go to war. It is to become more vocal and outspoken publicly. Then it is to reciprocally respond. Then it might or might not escalate.
We are still just dancing with each other. We’re just arguing over who’s leading the dance. The current aggrieved party being the one leading the dance for now.
As you said it appears that Maersk is probably one of the best practical choices for taking on this job. It’s back in the hands of an ally who’s capable of the job and trustworthy enough to not abuse it for state security reasons.
It’s also a temporary stop till a complete bidding process can be implemented.
I would point out though that the blow China has taken in Panama is every bit as significant as Maduro being snatched.
Those maneuvers are way beyond reciprocal in nature.
Just as Panamas Supreme Court ruling invalidating Hong Kong’s CK Hutchins port contracts there.
Australia is reviewing a 99 year lease with Chinas Landbridge lease of port Darwin.
It is important to note why, National Security concerns. Australia isn’t going at this through some contractual loophole.
They just rolled out the Nat Sec reason. Hard to assail or refute. And it’s also a fog horn of a message to China. This is not an economic or legal issue. We are recognizing your advances as a national security concern to the nation of Australia.
That nations like Panama and Australia are taking these steps. Or that European allies are being allowed to capitalize on economic opportunities uncontested.
Says more about what is happening behind the scenes than what is being said publicly.
China overplayed their hand with their recent circumvention of Australia, and live fire exercises in the Tasmanian sea between Australia and New Zealand. Not a good pictograph.
These are the real power plays taking place right now.
And it certainly looks like the US has more cards to play than China.