It's not realistic, because you will never consider every possible attack scenario. You may have considered timing attacks, but if you don't consider the way that the processor uses power when running through your algorithm, you may have just leaked key material. This sounds like an obscure case, right? Except that the Trezor bitcoin security appliance was just broken in that way last week.
Secure crypto comes from a lot of smart people repeatedly trying to destroy an algorithm and its implementation. It doesn't come from a super smart person building a cryptosystem; that's how we end up with DVD CSS.
The attack scenarios you described are against an implementation whereas I said your statement regarding protocols was too strong. Having that in mind, our comments don't disagree.
The format of a discussion does not necessarily have to follow a strict pattern of point->counterpoint->point->counterpoint->win in order to be meaningful or useful to the participants and spectators.
Secure crypto comes from a lot of smart people repeatedly trying to destroy an algorithm and its implementation. It doesn't come from a super smart person building a cryptosystem; that's how we end up with DVD CSS.