Here's the clause from their policy document:
"It meets any legal requirements and driving laws that apply – for
example, it may need to be taxed and have a valid MOT certificate.
We can check these details when you ask us for help."
Personally, I don't see the relevance of tax and mot as a contributory factor in a breakdown situation and it just smacks of a get-out clause to me. What if, for example, your car has been laid up off-road for a while and you want to MOT it so that you can tax it but can't start it? What if it had a cracked windscreen, faulty lights, empty washer bottle etc. etc? Are the AA/RAC/other recovery schemes the same? Worth keeping an eye on your MOT due dates if that is the case