You are confusing the cartel's transactions with the non-cartel transactions. The later are the ones that get delay. The cartel's miner excludes them when adding a block solution to the block chain.
So basically you say the cartel will for bigger future profits, now not reap the profits of non-cartel transactions. (that do give transaction fees, transaction without fees I now disregard, as i find it normal nobody wants to work for free...)
So analogy in the ´real´world in the sense that a cartel of shops somewhere lower their prices substancially, running losses, to outdo other shops to bankrupcy, and after that raise prices and earn a lot of money ?
Also I noticed you talk about 2 things: firstly a cartel not forwarding transactions to other miners, secondly a cartel not accepting transactions from non-cartel members.
And realize that because of those 2 things, this is horrific case where the cartel can both continue to profit on the transaction fees, i.e. it doesn't have to sacrifice by offering lower prices, and depriving the non-cartel miners of (increasingly greater share of) income while also depriving the non-cartel merchants and their customers of fast transactions.