With regard to the bi-modes required for MML intercity services. the ITT states that a prototype/demonstrator must be available by December 2021, and that the new trains must be introduced into service from May 2022; the lowest risk option regarding this delivery requirement, therefore, is to endeavor to procure a fleet of class 802s/802 derivatives.
However, the bi-modes must be able to match 222s for both sectional and total journey times; moreover, I haven't checked tonight, but I'm reasonably sure that it says somewhere in the ITT that any new or brought-in trains must be compatible with existing infrastructure. Therefore, I believe it is reasonable to assume that - as none of the IET family nor GA's bi-mode FLIRTS are listed as being able to use enhanced speed restrictions marked HST - trains which meet the DfTs requirements when considered in their totality are currently unavailable.
Aventra bi-modes MIGHT be able to match the performance of 222s, be suitable to take advantage of enhanced speed restrictions marked for HSTs, and therefore able to meet the total journey time/point-to-point journey time requirements of the ITT, but saying that they will be available to meet the delivery/entry into service requirements of the ITT is, I believe, very unlikely; having a brand-new train design entering service in three years time is theoretically doable (and was often achieved by BR), but the fragmented structure of today's railways and the complex approval process makes it extremely risky and very unlikely.
Non-compliances with the specification are discussed elsewhere; with regard to bi-mode trains for intercity services, it is probable that each bidder would have put forward a number of non-compliant proposals, leaving it to the DfT to decide which non-complaint offer it wanted to accept - either a class 802 or 802 derivative which couldn't match 222 performance but be available for traffic in accordance with the DfT's requirements, or a new train which met the DfT's performance requirements but not its delivery one.
Which way the DfT will "jump" when faced with these two options will be interesting to see; it "sold" cancellation of the MML electrification by convincing MPs with East Midlands constituencies that bi-modes would be, at the most, only one minute slower between STP and SHF than electrics, so late delivery might be an easier "sell" (to MPs) than significantly worse performance/longer journey times than now.
It might also argue that Aventras are the best option for the MML because they will be assembled in Derby which is, of course, on the line of route!