The biggest single tx in the world?

[el kaka22]

Today I've seen this tx: https://blockchain.info/tx/9fdbcf0ef9d8d00f66e47917f67cc5d78aec1ac786e2abb8d2facb4e4790aad6
It have almost 1,000,000B in size, have 7350 inputs of 1000 satoshi, paying 0.0735 as fees and have zero output. However this tx occupied the whole block 364773.
So strange?

[gmaxwell]

This is F2Pool;  see #bitcoin-dev earlier today where I gave wangchun a patch to produce unusually small, regular, and fast to verify signatures for the special case of spending a non-private private-key.