initonloosepolicy=1 would not help for previous DP tapes, it only helps for tapes reported to DP as blank.
If you import the tapes (can take a long time), recycle them to take off protection, if they are in the correct media pool, DP should try to use them.
But probably best just to spend the time force formatting them to the Media Pool where you need them.
I don't think there is a short cut.
You might be able force format using the command line, possibly script it.