Most probably, it was with this in mind that Satoshi introduced his 1 MB block size.  When he introduced it, 1 MB was way larger than any reasonable block at that time, so it was a good "miner directive" to say that blocks larger than 1 MB should be considered as spam (given we measured blocks in KB at that time).  It was a "good miners' directive" not a "protocol standard".  The idea was most probably, in Satoshi's mind, to give a clear rule to the miners as what was to be considered "prohibitive spamming".  It could systematically be put a factor of 100 or so above the "usual block size".   It was a trivial formalization of the good practice "don't accept obvious spam in the consensus decision".