I don't really understand this reasoning. Both hydrogen fuel-cell cars and EVs ultimately use an electric motor as the drivetrain. The difference is energy storage. Of course in-house designed batteries would be optimal, but generally lithium batteries and controllers are available off-the-shelf. So at least some of Toyota's investment into electric motors and the related controllers would still bear fruit with an EV, and they have the cash to go get batteries on the market until they can spin-up their own in-house solution.

So what is the problem?