Exactly this. I've seen cases where a prosecutor has gotten a John Doe warrant to send to cell companies that effectively asked for the IDs of all phones that were present the closest cell tower at the times of multiple robberies (eg "give me all phones that were present at ABC tower on Monday at 1pm, DEF tower on Tuesday at 4pm, AND GHI tower on Thursday at 10am). Which obviously only the robber is likely to show up on. To me, they're effectively searching my data even though I don't meet all the criteria because I was only near one tower one day. This is way different than what the court did to Smollet. They already had tons of dirt on him - and thus probable clause to dig deeper.

I'd be weary of them using this data to try to go after him for some obscure crime completely unrelated to the false report (e.g. pics of him walking his dog in a state park that forbids pets).

They did this very thing to associates of Trump in the course of the Mueller investigation. Unrelated tax issues, failing to register as a foreign agent and other charges were brought against certain individuals for things they did years before they joined the Trump campaign. Whatever your thoughts are on this, there is already established precedent for it.

Which all seem like notable things to encounter when doing an investigation like that and to not drop when encountered? 'Let's look if money was sent from x to y. Get bank and tax statements. Well (it didn't come from x but) it sure as hell wasn't taxed'

It's not like this was brought up as part of a single court case if not related which would make it a relevant precedent here.