The earliest angiosperms appeared in the Cretaceous. This is after the appearance of Hymenoptera (Jurassic) and Diptera (Triassic). While a nice story, this needs additional substantiation. An alternative explanation is likelier imo.

The early Hymenoptera were predatory, like wasps still are.

Bees, which feed on pollen and nectar from plant flowers, instead of catching other insects, have evolved much later from wasp-like Hymenoptera, after angiosperms were already widespread.

So the timeline fits into the story.