Maybe I’m just face-blind or being dense but the photos from the scene of the crime look like a different dude than the ginning hostel check in guy. The jackets and backpacks are different. Although people can have multiple jackets and backpacks. We don’t see much of the shooters face but the eyebrows look different. Although, people can pluck/shave eyebrows. I guess the happy hostel guy would have come forward and been like “WTF?” and “I have an alibi” if it wasn’t him?
Assuming he was elsewhere on CCTV at the time of the shooting (work, university, cafe) he should be ok.
Something I’ve learned in life is that should be and is are not the same thing. You’re right, that he should be okay, but the cops are going to want to stick this to someone. It’s way too high profile for them to let it go. If happy dude isn’t their guy and walks in the front door, the cops would make him their guy.
Facts. Dudes best bet is a lawyer and to lay low.
If that was me, there’s no way I’m walking into a police station on my own.