I was, in fact, never in direct correspondence with WOTC legal.
I did receive an email from Rich Redman, then Brand Licensing Manager, but not a lawyer. He wanted me to cease distribution of OSRIC. His grounds were that OSRIC was not compliant with the D20 license.
I wrote back to Mr Redman and explained that OSRIC didn't pretend to be compliant with the D20 license, and was in fact entirely reliant on the OGL.
Mr Redman apologised for not adequately doing his homework and then said he wanted me to cease distribution of OSRIC anyway. His basic point was the duck test: OSRIC looks like 1e, it quacks like 1e, so in his view it must be wrong to distribute it.
I replied highlighting various points of fact and various representations WOTC had already made, both in public and in private correspondence.
Mr Redman said this was beyond him and he would get WOTC legal to contact me.
This was in August 2006 and I'm still waiting for their email. I suspect they've figured it out, though, and will never pursue the matter.
The subtext behind OSRIC, and all the other retro-clones, is around computer gaming. You see, there's a duck test there too: a lot of computer games are, in their underlying concepts and algorithms, very similar.
Representatives of computer games companies are very interested in the possibility of a precedent that would establish, in US copyright law, exactly what constitutes a "rule" and what constitutes "artistic presentation". Any lawsuit involving OSRIC and WOTC could establish important precedents.
What that would almost certainly mean is an awful lot of money in amicus curiae. I don't particularly want to go there, and I think it likely that WOTC don't want to go there either.