What is acceptable as proof to you?
A deterministic way to link inputs to outputs for users who are not a "whale" relative to the other participants in the round.
He talks about both inputs and outputs. For the former gives an example of an entity which has received multiple donations in the same address (and which I agree with), and for the latter when an entity wants to make multiple donations to the same address (which besides unusual, is just not what the front end displays as an option). There are quite a few reports of Wasabi reusing receiving addresses when automatically coinjoining, and none of the victims wanted to donate (otherwise they wouldn't report it as a bug).
The quote I mentioned has nothing to do with inputs or donations, Peter Todd explains that when you use a deterministic seed on two different clients, they will each generate and use the same addresses:
That's not Wasabi fucking up, that's Wasabi users fucking up. Wasabi, they fundamentally, are not in a position where they can go and prevent people from installing the same seed in multiple wallets at once and using it in multiple wallets at once.
Being a Bitcoin Core developer doesn't grant you any ethic superiority. He's sponsored by Wasabi, and is being paid by Wasabi. Why isn't he considered a "shill" like you claim us to be with mixers?
Peter Todd is not sponsored by Wasabi or paid by Wasabi.