you dont need to extend the confirmation periods,, for over a decade now services have always followed the guidelines that if someone is spending $millions to wait 6+confirms to deem it settled. because if you DO THE MATH(said many times)
to go back certain amount of blocks to rewrite those blocks and then catch up and over take the network with a certain amount of competing hashrate takes alot of that hashrate cost to achieve.  [...]

With 55% of the hash power, it will take, let's do some math: 55% × (6 blocks/hour) × t > 45% × (6 blocks/hour) × t + 6 blocks  <=>  t × (6 blocks/hour) × (55% - 45%) > 6 blocks  <=>  t > 6 blocks / (6 blocks/hour × 10%) = 10 hours.

In an earlier reply, you agreed that a 51% attack from Ethereum could last for several months in principle. (And in fact, if they go absolutely all in on the attack, then it could even be many years, at least in theory, as mentioned in my preprint.)

[...] and services can also delay the withdrawal of the funds so the attacker wont try instigating the attack until after the withdrawal clears to ensure when they finally go backward X blocks they get to truly double spend. it then becomes unworthy of attacking the network just to get a refund, because CEX have other mitigating factors

You seem to be hung up on the confirmation time. But even if the attackers exchange their BTC back and forth for USD (rather than trade them perhaps more quickly for tokens or ETH), you still agree that it only takes a few days at max for each confirmation. Now, whatever confirmation period there is, this is something that all traders have to deal with. Yet there are still being traded BTC worth billions of dollars each day, despite these long confirmation times! You must agree that with enough money and backing, there is nothing stopping the attackers from trading many millions each day on average (and in principle, it seems that they might be able to trade upwards of billions).

So do you see that we don't really have to discuss the current confirmation time here; not when we are talking about a long-range attack that could rewrite months of the ledger?

as for manipulating the market price.. the market price is based on centralised exchange market orders on THEIR databases.. not the blockchain. so run some scenarios nd realise the separation between blockchain attacks vs market manipulation and realise if your end goal is "market crash", that there are easier methods that could have better success rates at less cost, compared to your un-thought-out scenario of thinking a 51% attack will affect the market as much as you assumed without thinking

run some scenarios. and try thing out. learn how bitcoin works, learn the mechanics and economics of bitcoin and what affects what