Capturing Maduro is not even close to conquering the entire country. Even ignoring the diplomatic fallout of actually conquering land instead of creating puppet states in modern politics, if the emptied armories are true it's probably not worth the heat right now.

The likelihood of a properly hot civil war there is higher than ever now. Let them shoot each other until they're low on bullets/people or sell off their arms on the black market before even considering that.

Hell if no clear government arises out of that ensuing chaos, if the US gov offered to buy those weapons at 10x black market value, a bit of stable infrastructure and bureaucracy, and some military "protection" against the remaining armed insurgents. Then they might be able to effectively buy the remains of the country for a fraction of the cost of an actual invasion.