Edit: To elaborate,
Threat - A declaring of one's intention to cause harm or loss to another's person or property or to limit one's freedom to act in a lawful voluntary manner (a threat to kidnap).
Harm to a person or property is not inherently present when talking to someone on the street.
This does not imply "a pleasant conversation of a few minutes on the street". This implies, given the past and present behavior of law enforcement at all levels of government, "ending up in an interrogation room for several hours during repeated questioning attempts, before being dumped on the street somewhere random after refusing to answer questions without a lawyer present".
Why do you feel like you can confidently say that? First of all, they never say they intend on detaining her. Secondly, there is zero precedent for what you're claiming is implied here. Thirdly, "happen to run into her on the street" does imply an ad-hoc conversation and not a formal interrogation.
You're drawing conclusions without evidence, why do you think that's an okay thing to do?