[condiment]

https://pubs.acs.org/doi/pdf/10.1021/acsptsci.9b00048

^^ Here's an article written by Lotte Knudsen, referenced in the original post, that further tells the story of how GLP-1 was first developed into a drug (as liraglutide) and approved for human use. There were a lot of false starts and additional practical problems that needed to be solved in order to yield a viable medication.

After reading the OP I was surprised to learn that Novo Nordisk picked up the research only a couple of years after GLP-1 was abandoned by Pfizer, after which it took 5 years to develop the initial medication and another 12 years to make it through FDA approval. Even after all that, the primary indication was for diabetes. It took another 7 years for semaglutide to make it through approvals and bring GLP-1 into the public consciousness.

When you consider the amount of time involved, and the sustained investment required, it's difficult to fault the execs at Pfizer for their decision to shut the project down. Obesity wasn't nearly as prevalent then as it is now, and it seems likely they had funded the startup specifically because of the author's prior research into nasally-administered meds. It's even possible that the shutdown decision had little to do with the primary area of research.