Don't put too much hope into that. I doubt WotC has too much influence on Larian now although it would depend on the actual contract. But even if WotC threatens to not make future deals with them, which is probably the worst thing they can do, Larian has its own IP and does not depend on it. I also doubt that WotC has a problem with Larian bending the rules. They are on a big D&D marketing offensive with games and the upcoming movie, so likely care more about a flashy presentation and name dropping than staying true to their rules. Especially as with the recent books WotC has started to modify rules quite heavily themselves.
Could we count on your signature for the petition ?