guesstimating on a level of: "hey it is 500k so i pay 10k and if it is 0.05 I would splash 20k out" doesn't work and it is being punished by the prolonged wait
I'm afraid this might not have been a spam attack (whatever you might mean by this). Yesterday, there were quite a few blocks that had a lot free space in them (note, I didn't consider empty blocks), and this is in striking contrast with what miners are doing today and what they had been doing just before yesterday. Whoever might want to strongly disagree, may also want to check the blockchain for themselves...
So, it looks more like some miner attempting at getting more fees than someone spamming the network