Great!
For instance, this allows you to import your TREZOR word list in case your device was lost or damaged so you can quickly move your funds to safety.
Just for the sake of symmetry... Can I also use word list generated by Mycelium during HD account backup as input for Trezor?
Yes, but have in mind that Trezor provides higher security than what you can get on an android device, and by having the same master seed on two platforms gives you the least common denominator... Security wise.
So, I would only do that if my phone was broken.
Of course. Having the same master seed on two platforms is not the intended application. But in the case your phone is stolen/compromised (or broken) it is faster to use Trezor (if you have one) to temporarily protect your BTC than to get another android phone and install Mycelium. I know you can use backuputil too
I have both Mycelium and Trezor and I intend to use them both :-).