Parallel structures

[Mhsn]

A sentence below from my test book made me hesitated in using had that I thougt that did should replace had because of the rule of parallel structures. Can you share me your opinion please?
The sentences is "The final speaker gave us more details than had any of the previous speakers."

[Dozy]

It seems OK to me. It's an inversion of "The final speaker gave us more details than any of the previous speakers had (given us)." The previous speakers precede the final speaker, so the past perfect seems justified.