I may be missing something here
I think specifically “new age” here is referring to water-divenation, this is where some person claiming to be able to detect water gets a divining rod, which is often just two sticks and claims the sticks can show them where to dig a well and hit water (you can look up videos of it on YouTube). They often walk on strange paths, or stagger around and around fields in this process.
So I guess these guys are doing something similar with construction related tasks.
EDIT: I’ve seen it suggested elsewhere that Gary Larson was particularly annoyed with New Age music, and found it repetitive:
I was thinking it was a crystal-dangling thing. Know how they put one on a string and let it swing?
I believe both of those are considered types of dowsing
