Dilier, like Terpstra vs Kristoff in Flanders, knew that if they got caught, he would go from 2nd (a dream result for him 6 hours before) to 3rd, or 8th, or worse, in a hurry.At least Terpstra stopped working near the end after it turned out that he wasn't stronger than Kristoff on the cobbled climbs. He got a podium in the RVV and forced the other guy to do the work near the end. Dillier on the other hand didn't stop taking turns, not even durning the final 5km and was actually leading Sagan in the Velodrome. You can ride for a podium, but at one point you usually start to let the other guy to the work so the you have at least a small chance of beating him.
Also, it's not unprecedented to choose to start a sprint from the front. Witness Sagan in San Remo this year. Now, obviously it's not often a good idea, but there have been plenty of instances where it's worked out (it usually doesn't), and on a velodrome is one of those situations where you can use the bank to help you (Dilier didn't do a good job of this).