"Screwed" is probably an exaggeration: that's only 3% on one block and the node lost these 3% too. That could be unintentional too (a freshly restarted node which didn't have the time to fill it's memory pool will generate a block with fewer transactions).

What's important is that it's not an exception: that's the second time I check recent P2Pool blocks and I found that they were small ones which missed potentially higher fee income.