It seems that Maurice Walshe was also of the opinion that the first five higher
knowledges are mundane. See his note 136 to the Samannaphala Sutta, [Walshe 1987, p.547]
136."All the preceding 'fruits' have led up to this, which as RD points out, is
exclusively Buddhist..." - [Walshe analyses the sequence into 13 stages.]
Stage 12."The five mundane forms of 'higher knowledge' (abhinna), (verses 87-96)."
Stage 13."The realization of the Four Noble Truths, the destruction of the corruptions
(= the sixth, supramundane, abhinna), and the attainment of Arahantship (verses 97-98)."
That these first five knowledges are mundane is very clear in the Samannaphala Sutta
sequence (DN 2).
"With his mind thus concentrated, purified, and bright, unblemished, free from defects, pliant, malleable, steady, and attained to imperturbability, the monk directs and inclines it to the knowledge of the ending of the mental fermentations. He discerns, as it has come to be, that 'This is stress... This is the origination of stress... This is the cessation of stress... This is the way leading to the cessation of stress... These are mental fermentations... This is the origination of fermentations... This is the cessation of fermentations... This is the way leading to the cessation of fermentations.' His heart, thus knowing, thus seeing, is released from the fermentation of sensuality, the fermentation of becoming, the fermentation of ignorance. With release, there is the knowledge, 'Released.' He discerns that 'Birth is ended, the holy life fulfilled, the task done. There is nothing further for this world.'"
He discerns 'this is the way leading to the cessation of stress ...', this means that
he sees the noble eightfold path, enters it, and by developing it, he attains awakening.
So the five previous 'higher knowledges' were attained while the bhikkhu was still an