There's a number of reasons I think, including:
1. The fossil itself is beautiful and outstanding
2. There is less pressure to produce right now given oversupply and shipping constraints in Alberta
3.Suncor cares more about its reputation than some of the other players in the tar sands
4. The Royal Tyrell Museum is well known to most Albertans, kids go there on school trips and it would likely seem like the obvious thing to do (stop work) when presented with such a find.
5. I have no idea if there is a finders fee, but that fossil is probably more valuable than anything that loader was processing all day.
6. It's a dinosaur - most folks find them pretty cool. :)