Perhaps, but I feel that anyone sophisticated enough to replicate my fingerprint perfectly before it reverts to password only, and to do so before I'm able to make a remote wipe, and able to even find my fingerprints (lost phone) and to be lucky enough that the fingerprint is the one I used to secure the device, makes this a sufficiently low risk to the average user in my opinion.
If you're at odds with an American TLA, your 4 digit pin isn't going to slow them down at all.
Besides, the entropy on the average 4 digit pin is really low, it has a greater chance of using 5, 6, 8, and 9 for righties, and 4, 5, 7, 8 for lefties. Combine this with repeated finger grease blobs, and I don't feel anyone can logically argue that a pin is a sufficiently more secure option compared to a fingerprint.
Sorry, I should amend that last statement to be using the model Apple is using with it's touch ID where the fingerprint simply authenticates use of a high entropy password stored on the device, and the datum of the fingerprint is in not sent.
If you're at odds with an American TLA, your 4 digit pin isn't going to slow them down at all.
Besides, the entropy on the average 4 digit pin is really low, it has a greater chance of using 5, 6, 8, and 9 for righties, and 4, 5, 7, 8 for lefties. Combine this with repeated finger grease blobs, and I don't feel anyone can logically argue that a pin is a sufficiently more secure option compared to a fingerprint.