Here we go again, but isolated and clearly this time:

Sprint had valid reasons for filtering. ... ^^^^^

Oh yeah? Did they think so? Who else has any voice in whether their reasons were valid? Frankly my dear, if Sprint or any other provider wanted to filter all prefixes containing an odd number of bits, and if they thought they had a valid reason for doing so, then by definition, their reasons would be valid. *Our* opinion of the validity (or not) of their reasons would be *irrelevant*. MIBH used to run with prefix filters. It didn't stop much but what it did stop was worthless -- not just people chopping up their ARIN blocks, people doing cheap distributed load balancing by emitting a prefix from multiple locations as a way to do cheap distributed load balancing(*), but erroneous garbage that never should have been there, and so, wasn't. At least in our view of the net. Our customers were happy, so, so were we. (*) if you want to do cheap distributed load balancing by faking multihoming of a prefix, you'll need swamp space, which seems like a small fence to climb.