Straightening a 7" x 2" joist. (UK)

That's an assumption. He might use lots of short brads that generate enough shear between the floor and joist but too short to penetrate the glue. You don't know what someone will do in general. That's why there's a code - tell them the minimum of what to do and what not to do.

There's a big difference between glulam and some guy gluing up a bunch of wood in a shop. The former is covered by code, the latter is not (well, not directly...). There's a good reason.

Around here, he's talking about less than C$30 worth of joists. That's Cheaper that fiddling in my book. I'd buy new wood and use the old for other projects.

Mike