Re: [POLL] Possible scaling compromise: BIP 141 + BIP 102 (Segwit + 2MB)
Bitcoin already has a sigops per block limit to mitigate the risk of this attack (despite the FUD that introducing such a limit is all that's needed to solve the problem, which is pretty dumb considering that's already what happens 
)
who the damned F*ck should be allowed to build a single tx that uses 20% of a block!!)who the damned F*ck should be allowed to build a single tx has 16,000 sigops!!
Bitcoin is permissionless. The proper answer to "who the damned F*ck should be allowed to build..." is anyone who wishes to.
But another aspect of permissionless is the fact that no miner is compelled to include that transaction into a block. In fact, there is a natural disincentive to any miner including such a transaction into a block. Blocks that take a long time to validate are likely to be orphaned by other blocks which validate quickly.