We have no idea what the timeline was, so this is just a guess.
JP is simply an employee, it's not his company or nickel. Why not sit in a hotel room and wait for further instruction on what to do. He's on the clock.
Andy arrived in Colorado the day after Suzanne went missing. That night he talked to Barry and asked him the questions about employees, how they were paid, if any of them had been to his home, etc. Barry offers up the story about the employee who lived in Salida, the one he supposedly told to stay away from his family.
If Barry told Andy that story, he also told LE the same thing. So LE is going to high-tail it over to this employee to check him out. This likely happened within a day of Suzanne's disappearance.
So now the employee is being questioned about his bosses missing wife, after being thrown under the bus by ole Barry. Wouldn't it be natural for him to be suspicious of Barry's motive for directing LE's attention to him?
Wouldn't he tell LE about the hotel room, mail and anything else he observed? IMO his behavior was completely normal, he told what he knew and handed over what he found in the hotel room. As far as reading a letter which had already been opened and was laying around, don't blame him there either.
I would suspect JP was either questioned at the hotel, or immediately upon arriving back to Salida. The timeline was likely 2-3 days after May 9th, MOO.
