FRONT radial tire?

I have some interesting information regarding tires (and the Metzeler we spoke about in particular).
Here a couple quotes from a couple emails from the top of the Metzeler and Pirelli command:

'The ME880 and the ME888 are interchangeable unlike other lines but please note the following regarding mixing of radial and bias tires as it is extremely important. If there is a radial and bias used the radial can only be mounted on the rear and the bias tire on the front.'

'Yes depending on the bike it is ok to run a bias ply front tire with a radial rear tire. You just don’t ever want to go vice versa and run a radial front with a bias rear. There are a few BMW and KTM original equipment applications that run a bias front with a radial rear but it’s not a very common practice. So again it all depends on what kind of bike you are putting these tires on. But application-wise it’s acceptable to do.'