As I said, I've already started down that road. I've made similar changes and know what code is needed. However, I won't waste my time finishing it until someone can convince p5p to accept it. The amount of work is not trivial due to some accumulation of hacks in how 2-arg vs. 3-arg open are handled. And I'm convinced p5p won't accept such a patch anyway.
I also refuse to try to convince p5p. I don't find them to be very susceptible to (my) logic. q-: (or, if you prefer, because it wouldn't work anyway -- someone else would have better luck convincing p5p)
See my p5p submission for more details.