There’s a lot more going on, in the political world, that’s contributed directly to Sig Germany’s demise.
The US perspective is probably that the DOD Contract for Sig USA was a GOOD thing for the company... in reality, nothing could be further from the truth. In the current world political climate, no European Government would want their arms manufacturers winning and servicing US DOD contracts. The Sig USA - Sig Germany “importer” model became an embarrassment that was just too easy to target. From a European perspective, the Columbia Shenanigans was just the excuse Germany needed, to lead Sig Germany out back behind the barn...
We sometimes forget over here, how much the EU Governments detest our current political “leader”. In their own words*, they see a leaderless US ship about to run aground, while a madman rushes around the deck, telling everyone who will listen how great he is. Any German company with a US subsidiary handling US contracts is likely doomed... unless a November Election result appears to start healing the chasm of hate between the EU and the US.
*
https://www.politico.eu/article/donald-trump-eu-strategy-nothing-g7-summit-angela-merkel/