==> what "orphaning effect" ? Orphaning occurs when OTHER MINERS decide to mine upon ANOTHER block than the orphaned block. If miners decided to mine upon block A, with blocks B, C, D and E, there simply isn't any other set of blocks around that a P2P node could "prefer". Suppose that a majority of P2P nodes decides to "orphan" block B. But the miners have been building blocks C, D and E on top of B. What happens ?
Well, these nodes stop. They stop at block A. And they can't find any other block that pleases them. B wasn't according to their taste. But there's NO OTHER BLOCK around that is built upon A. Nobody has ever made a block on top of A with a higher PoW than the chain B,C,D,E. In fact, nobody ever made a block on top of A.
but then pools see that all the merchants cant see their rewards for BCDE..
the users waiting on transactions cannot see BCDE
Of course they can if they configure their wallet to connect directly to a miner pool node ! And do you think that a merchant or an exchange is going to stop its business for a day, while the competition accepts the new rules on the chain, and gets its node and wallet up and running again ?
Suppose that miners have announced that you should configure your node to 1.2 MB, because otherwise, you won't be able to see their chain. Now, suppose that you need to send or receive 100 BTC for an important deal. What are you going to do ? Stop your node ? Or accept their change ? Suppose you are a merchant. You simply want to be able to get bitcoins, and to send them for conversion. You don't care about the technicalities, you simply want to use it. What are you going to do ? Connect to a stopped node, or connect to something that sees the current chain and accepts transactions ?
Suppose that you are an exchange. Are you going to block withdrawals and deposits from customers, or are you going to update your node to suit the new chain ?
As you say, the miners can wait to spend, they even have to wait to spend ! They just keep on mining the same chain, and you can chose to join them, and see your funds and be able to transact, or simply do nothing. You upgrade, you are online again with bitcoin ; you don't upgrade, you are off the chain and off bitcoin. What are you going to do ?
As a user, you are rather agnostic, and just want to use bitcoin. As a full node owner, you can chose to have your node halted or to agree with the miner's protocol. But by doing so, you are just going to get a user to ignore you, because the user wants a working chain to be able to transact on.
so way way way before z4 (z4=going through the alphabet 4times(100 block confirm maturity)) occurs just to spend B.. pools realise they better make blocks according to rule A otherwise they have wasted half a day building b-zb-zb-zb-z that would be unspendable.
Of course it will be spendable. Nobody else can in any case spend what so ever during all of this time. All those not accepting the chain are "taken hostage" too. So who's going to give in first ? The mining pools, that eventually would like to sell their coins, or the nodes that serve the users, that cannot do anything on the network any more until they accept the new chain ?
Remember that most users don't have full nodes. There are millions of users, and only a few thousand of full nodes. Users have wallets that connect to a reference node - this could just as well be a miner node.