In the first place, the Secret Service does have police powers throughout the U.S. to enforce federal laws, specifically those relating to financial crimes: currency counterfeiting, financial fraud, wire fraud, etc. Any expansion of those powers comes from Congress and not the governor of Colorado. In the second place, the legislation gives them the authority to respond to non-federal crimes committed in their presence, or non-federal crimes that have been committed when a Colorado law enforcement agency requests their assistance. This has nothing to do with arresting local sheriffs. If a local sheriff violates a federal law then the feds don't need permission to arrest them, and it likely wouldn't be the Secret Service who does the arresting.
Um, you just made the point of the article. The ability to make arrests for non-federal crimes like State gun laws. The Governor has no one else to call on to make those arrests so they need a federal agency like the SS to be able to do so.
There you people go again, actually thinking the Rats respect the laws.
Except for the part about arresting for violations of federal laws, the SS has the same power as any citizen of the US when it comes to enforcing state and local laws. . .you know. . .citizen arrest powers.
Colorado, it appears, is trying to deputize in some way the SS.