Onomatopoeia

Everyone is familiar, I take it, with the following passage:

the natural grammatical transition by inversion involving no alteration of sense of an aorist preterite proposition (parsed as masculine subject, monosyllabic onomatopoeic transitive verb with direct feminine object) from the active voice into its correlative aorist preterite proposition (parsed as feminine subject, auxiliary verb, and quasimonosyllabic onomatopoeic past participle with complementary masculine agent) in the passive voice

None of the sources I’ve seen propose an onomatopoeic explanation for the verb in question here (and I’m actually curious about who the first person was to spell that out in print), and I wonder if that’s not a curious intrusion of Bloom’s incomplete information about the world and word, similar to “aorist.”