If I look in the corpus of contemporary American English, I mostly find the "..greater than I am/he is/etc... version. But there are a couple of instances even in academic texts of the sort "..greater than myself/himself etc..." sort.

As far as I understand the rule, comparative + than is followed by a clause - i.e., subject and verb. Where do the reflexive pronoun "...self" instances come from? Am I missing something, or are they just falling for the "looks like an object position, so let's use an object pronoun" trap?

If I look in the corpus of contemporary American English, I mostly find the ... greater than I am/he is/etc. ... version. But there are a couple of instances, even in academic texts, of the sort ... greater than myself/himself etc. ... sort.

As far as I understand the rule, comparative + than is followed by a clause - i.e., subject and verb. Where do the reflexive pronoun ...self instances come from? 

Am I missing something, or are they just falling for the "looks like an object position, so let's use an object pronoun" trap?