The mayor's comments came during a meeting attended by Thornton two weeks after he was forcibly removed from the chambers. Swoboda had said the council considered banning Thornton from future meetings but decided against it.
Thornton said during the meeting he had been issued more than 150 tickets.
In a federal lawsuit stemming from his arrests during two meetings just weeks apart, Thornton insisted that Kirkwood officials violated his constitutional rights to free speech by barring him from speaking at the meetings.
But a judge in St. Louis tossed out the suit Jan. 28, writing that "any restrictions on Thornton's speech were reasonable, viewpoint neutral, and served important governmental interests."
Gerald Thornton told KMOV the legal setback may have been his brother's final straw. "He has (spoken) on it as best he could in the courts, and they denied all rights to the access of protection and he took it upon himself to go to war and end the issue," he said.
Kirkwood is about 20 miles (32.19 kilometers) southwest of downtown St. Louis. City Hall is in a quiet area filled with condominiums, eateries and shops, not far from a dance studio and train station.
The police department's chaplain said law enforcers from several agencies were anguished over the shootings.
"They're all just so sad, shocked by this," said Father Robert Osborne of St. Peter Catholic Church. "This doesn't happen in Kirkwood."
Despite its reputation locally for serenity, the city has grappled in recent years with crimes that brought it unwanted attention.
Down the street from City Hall is the Imo's pizzeria once managed by Michael Devlin, who kidnapped 11-year-old Shawn Hornbeck in 2002 and held him for four years before authorities rescued him in January 2007. Also rescued was Ben Ownby, another teenager Devlin abducted just days before Devlin's arrest.
Those crimes got Devlin life terms on state charges, as well as 170 years behind bars on federal charges that he made pornography.
City Hall also is about a block from a park now named for former Kirkwood police Sgt. William McEntee, who was a 43-year-old father of three when he was slain in 2005 by a man who witnesses said blamed police for the death of his 12-year-old half-brother two hours earlier.
Kevin Johnson was convicted in November of first-degree murder and last week was sentenced to death.
Associated Press writers Jim Suhr in St. Louis and Betsy Taylor in Creve Coeur contributed to this report.