Look for evidence of chemicals, pipes/nipples, timers, igniters, or anything marked orange/red with caution stickers. If you don’t see any, you’re probably fine. Most of it looked like it would NOT be any use for bomb making. I used to make canons and things that go boom as a kid a long time ago and built lots of electronic things. Look for magazines or printouts for hints as to what his hobby really is. Cars, computers, electronics, gizmos..
People think that any device with an LED 7-segment display is a bomb. Because TV.