I haven't seen the tech sheet on that 2K but every one I've
seen on other brands has always said it's fine on small
spots of exposed metal, like silver dollar size or smaller.
So far small break throughs it's fine.
There are a lot of people out there that has done an entire
bare metal panel with 2K (urethane) primer only and it's held fine.
I did the same thing when I first started using 2K primer
on an entire car I stripped and it held fine, so I think it's better
than most would think.