All the of expensive operations can be done before a block is found, then they do not add any proportional time.

Alternatively, miners can just consolidate to larger and larger pools-- which don't suffer any of those delays between themselves. Historically, this is how miners have responded to higher orphaning.

Alternatively alternatively, pools can just implicitly trust each other's work-- this is functionally equivalent to becoming a single larger pool for the purpose of this discussion.

Even ignoring all this, in the absence of subsidy orphaning risk doesn't produce a non-negligible minimum fee (in other words, this can't be an argument for fees providing Bitcoin's security in the long run). Even ignoring that, whatever 'implied limit' that falls out has no reason to be a blocksize which is workable for keeping non-mining full nodes on the network, so no check on the miner's behavior.


Amusingly, all of these were pointed out in peer review on Peter_R's paper, and he agreed to revise it to at least make the assumptions explicit... but then did not do so.