The Ghash double spend was a pretty big deal, and instigated a big campaign by miners to switch away from the Ghash pool. So it was costly for the pool, and it was probably not happy about its employee executing it.
Any player that directly owns 51% of the hash power, rather than just pooling, would similarly be economically incentivized to avoid such double spends, as they provide very little payout, while undermining confidence in the protoocl.
Any player that directly owns 51% of the hash power, rather than just pooling, would similarly be economically incentivized to avoid such double spends, as they provide very little payout, while undermining confidence in the protoocl.