The core idea revolves around miners' response to being presented with a block that is expensive to validate. According to the outlined scenario, a miner would opt to discard a slow-to-validate block if a competing block arrives during its validation phase. This decision is based on a preference for faster, equal-work blocks over continuing to mine on top of the old tip. The strategy does not involve any deviation from the actions of regular relay nodes within the blockchain network.

The discussion extends to the natural occurrence of a race between a normal and an expensive block. In such instances, the propagation disadvantage of the expensive block could be exacerbated if miners, upon receiving it first, also start validating a subsequently received normal block in parallel. This approach would further diminish the chances of the expensive block being built upon by other miners. However, this proposal suggests only a marginal improvement in a specific unlikely scenario and comes with high implementation complexity.

Moreover, the possibility of a miner proposing a block that takes an hour to validate is considered. In such extreme cases, up to six competing blocks could emerge while the slowest node is still processing the first block. The crux of the matter lies not in the rarity of this attack but in whether the potential for an attacker's block to become stale acts as a sufficient deterrent against such strategies. The effectiveness of this deterrence could justify the complexities involved in implementing measures against it.

The conversation also touches upon the phenomenon of empty blocks, highlighting how SPV (Simplified Payment Verification) mining, due to its reliance on propagation time, currently stands as the primary cause of such occurrences. It's speculated that a shift towards optimizing for validation speed might introduce another reason for the emergence of empty blocks within the mining ecosystem.