LE is in a tough spot. They need to mover quickly and aggressively, given that this is a missing young woman case with a good chance that foul play may be involved. Yet, they have to play by the rules and anyone who come up as a POI has to be given his rights. LE, in such cases, try to give out as little info as possible, yet as much as they can to get people to step forward to give more info. It's a delicate balance.
My guess is that they have video footage of JM with Hannah to a point, but then that's it and it's not enough to hold JM as a suspect. We don't know what LE said to JM, or what JM told LE. The report that he had drinks with Hannah and they then went separate ways is not attributed to JM by LE, but by a news source who says his grandmother said this. Whether that is indeed what he told his grandmother or if it came from someone else who told the grandmother we don't know. This can be 3rd or 4th hand info. All we know is that there is not enough evidence to book JM, but enough to make LE suspicious of him.
My guess is that they have video footage of JM with Hannah to a point, but then that's it and it's not enough to hold JM as a suspect. We don't know what LE said to JM, or what JM told LE. The report that he had drinks with Hannah and they then went separate ways is not attributed to JM by LE, but by a news source who says his grandmother said this. Whether that is indeed what he told his grandmother or if it came from someone else who told the grandmother we don't know. This can be 3rd or 4th hand info. All we know is that there is not enough evidence to book JM, but enough to make LE suspicious of him.