There would still be conflict. The issue is that he had decisive control at Palace (UEFA’s verdict not ours), therefore regardless of what he did with his Lyon shares the perception is that he can influence a Palace performance.
So if he put his Lyon shares into trust then fine he has taken a step back from Lyon, however he could still use his Palace influence to try and change the result of a match.
The only way both teams could have gone through was for Textor to place the shares of both teams into trust, but as it happens there was no need with regard to Lyon because they went through based on the dodgy UEFA decision I referred to previously.