I understood it also to be a political issue at the time as the bodies would be built in Belgium and not Derby and thus not safeguarding / creating British jobs at the height of the recession.
Wasn't it was more that the cost was high and potentially with the electric spine some XC services could go electric.
Of course we already have an existing BI Mode in IEP it would seem to me that a small fleet should be considered for XC enough to allow the elimination of XC HST's some capacity increase and a possible cascade of Voyagers onto the Nottingham - Cardiff route freeing up some 170's.
I suspect a regional BI mode DMU will be regarded as to expensive even for the likes of TPX as will IEP for XC.