Marvel Comics loves to team its superheroes up far more than DC ever does. In the comics, this means frequent crossovers, enough to make you wonder whose book you're reading. On TV, it means guest heroes who don't have their own shows.
This often happens in the cartoons, but this TV movie -- the first of the post-cancellation Hulk specials -- was actually the first time Marvel tried it in live action. And it was only the second team-up of ANY live-action superheroes. (The first was Green Hornet guesting on the 1960s Batman show, an episode viewed more often than the actual Green Hornet series!)
I liked the Hulk series, even though his powers were limited for a TV budget. Bill Bixby's acting as Banner compensated for any change to the hero's motif. But he still was a gamma-charged powerhouse whose appearance was triggered by rage. Thor didn't survive as well with the Hulk's writers. He's not a Norse god here, just a revived Viking warrior. Donald Blake doesn't become Thor, he summons him from the hammer like a genie, with lightning instead of smoke. And Thor doesn't even get to fly. Or wear a red cape. And the acting doesn't compensate for these changes.
Apparently the writers were envisioning Thor as a "buddy" series spinoff. If Hulk was "The Fugitive," then maybe Thor would have been "Route 66"? I think the writers should have spent more time with comic book themes than with 1950s TV shows.