IMHO it does look like he stuck the tubes into the runners and then used either a reddish colored high temp epoxy or silicone to create a airtight seal.
I would hazard to guess the intake runner was machines to accept the manifold runner tube to slide in as the pipe doesnt look distorted and no welding or bolts to hold it in that I see.
I would hazard to guess the intake runner was machines to accept the manifold runner tube to slide in as the pipe doesnt look distorted and no welding or bolts to hold it in that I see.