Armstrong was active in the substance abuse testing industry, working as a vice president at Healthcomp Evaluation Services Corporation and then ClinNet Solutions.
While on the City Council, in 2010, he was appointed to the board of the Barron County Economic Development Corporation and was chosen as executive director of the organization in 2012—a position he still holds.
[4][5] Armstrong ran into significant controversy in September 2020 when a review of his Twitter feed found that he had been posting and retweeting messages from the QAnon conspiracy theory.
[7] A further review found what the Democratic Party of Wisconsin described as years of racism, misogyny, religious bigotry, and conspiracy theories in his feed.
In the days just after the 2015 Charleston church shooting, he posted a series of supposedly racist tweets, including one featuring a snippet of Ku Klux Klan leader David Duke.
[8] Armstrong was also apparently outraged by subsequent bipartisan vote in Congress to ban the Confederate flag, as he then promised to stop donating to the Republican Party as punishment for their act.