so long as you can stake your bitcoin address there is no need for a duplicate topic staking another altcoin's addresses. and it won't stop at ETH, you want ETH someone else wants LTC, another person another altcoin and so on. there will be no end to it.
Have you even read his reply? He just states that there isn't a ETH adress stake thread since this is a bitcoin forum. If you give in to that you'll soon need to give in to every shitcoin.
To recover your account? No, only signed messages from a bitcoin adress you staked are allowed. However i could see exceptions being made to that rule, but to say that it's widely accepted by mods/admins here is wrong. I wouldn't take my chances.
For more information about recovering your account, check out https://bitcointalksearch.org/topic/recovering-hacked-accounts-or-accounts-with-lost-passwords-497545 where the administrator explicitely states that proving ownership through a signed message with a staked 'BITCOIN' adress is the preferred way.