No, that's what gave them reasonable suspicion to detain him.
As to the spring-assisted knife, the same police report also said that it was a switchblade. The DA said it wasn't.
You apparently aren't familiar with how criminal laws are written. A common charge in Maryland is "Unauthorized Use of livestock". This is the charge for driving a stolen vehicle. The switchblade charge doesn't necessarily mean he had a switchblade. It is a categorical charge that includes assisted-opening knives.
any knife with an automatic spring or other device for opening and/or closing the blade, commonly known as a switch-blade knife.
This is a pretty vaguely-worded law (compared to switchblade laws in other jurisdictions). There is a difference between "automatic spring" knives and "spring-assisted" knives, so it's not clear whether a "spring-assisted" knife would fall under the statute. It would depend on whether the spring assist mechanism falls under the "other device" part of the law.
the police chief was being interviewed on CNN....he is tough lean man....said something to effect that, he was hired to clean up the PD, and would not tolerate any misdeeds...but 6 of his staff, according to DA, violated just about every rule in the book...