Police Stop

The argument seems to have two premises: (1) Taking pictures is legal, an (2) Michael took pictures.

Those premises could either be true or false, depending on the situation and the local laws.  If both premises were true, a resulting conclusion would be valid; if either of the premises were false, the conclusion would be questionable.

The logical conclusion from the two premises would be that it was legal for Michael take pictures.

However, that's not what the conclusion claims "What Michael did is legal."  There's a potential ambiguity fallacy here because it's not clear what the conclusion understands about what "Michael did".  If we're saying that Michael's action of taking the picture was legal, the conclusion could be valid.  However, in the narrative Michael did something else ... he also refused to answer a question.  Nothing in any of the premises speaks to whether it's legal to refuse to answer a policeman's question, so there's no way to tell if Michael's refusal is legal or not.  

In addition, the implication is that Michael did to something that's not legal – a "suspicious act".  The non sequitur about the suspicions act causes the argument to break down.  We'd need some premises about suspicious acts, whether Michael's actions were suspicious, and whether simply refusing to answer a question qualifies as "suspicious".

This would be a purely legal argument where the soundness depends on the law.  Either Michael broke the law or he didn't. Or perhaps, more specifically, either police have a right to detain people for "suspicious acts," or they don't. If the legal argument revolves around detention for suspicion, then second argument is a non sequitur — it doesn't matter if what he did was legal or not; it is the suspicion and the officer's right to detain for suspicion that matters. But again, knowledge of the law is really needed here.