Then, on June 1, the worst happened: Rosenberg suffered a massive heart attack. By the following day, he'd been declared brain dead and his family removed him from life support.
Rosenberg wrote "Everything You Need to Know About (Legally) Carrying a Handgun in Minnesota" and was a gun permit instructor. His activism took a strange turn in November of last year, when he posted a YouTube video of himself bringing a gun into the Minneapolis Police Department. Sgt. William Palmer demanded he surrender his handgun and when Rosenberg refused, Palmer disarmed him. Rosenberg was arrested a month later, and was due in court over the incident in August.
After his sudden death, the charges were obviously dropped, but Rosenberg's wife Felicia Herman says she's struggling to pay their mortgage.
"We used up all our 401K money and there was no life insurance," she says. "We're kind of broke."
Things only got worse when she realized that a PayPal account her late husband had set up to collect donations for his defense had been hacked. She says at least $1,000 has gone missing.
So, tonight at Dreamhaven Books, a collection of Rosenberg's supporters and friends will gather to hear music and contribute what they can to Herman and her two daughters. Herman says she'll also be auctioning off a couple of Rosenberg's most beloved guitars. His collection of firearms will also go up for sale, but is being handled separate from the benefit.
"I'm just amazed at how many lives he's touched," says Herman. "We're truly grateful for all the wonderful friends that have rallied around and helped us so much."