Technically no, because as vjudeu has pointed out, no one would join my chain anyway since I would have to hard fork to drop the difficulty like this. I was simply using it as an analogy as to why the longest chain is not synonymous with the chain with the most work.

For the longest/most work argument, it doesn't matter. Even one block more would be enough for all nodes to swap to the longer chain if this was the criteria being used.

If we did use the longest chain, then what would be possible would be a miner mining in secret while manipulating the time stamps on their blocks to artificially drop the difficulty. Theoretically a miner can drop the difficulty to 1 by incrementing the timestamp on the first 2,015 blocks of each difficulty period by 1 second, and then setting the final block's timestamp to the current time. If we actually used longer chain rather than most chain work, then a very small minority miner could reorg as much of the network as they liked.