No contradiction between Haematite and Olivine
read his latest work before shooting off, Barry.
He has a perfectly self-consistent model of a cold ice-rich frozen Mars plus formation of Haematite. PDF from 6th Mars here.
He has discounted the formation of Haematite in a cooling volcanic ash deposit, which doesn't even need standing water, but regardless, his model is of a largely frozen Mars with only local and occasional water.
Those local events are, of course, important. At these times, a long-lived deep subsurface biota may be brought to the surface where it might live for short times, but would be unlikely to adapt to the permanently harsh surface conditions, unless it can find refuges like my ice towers.