It is also entirely possible to honestly say you are not working on something that you have gotten the right to do so. Other than the initial discussions, D:OS 2 was the focus of development for some time, and there were a few updates out for the DE before the bulk of people started moving over to BG3. Fallen Heroes was also worked on for some time internally before we partnered with Logic Artists to continue development.
Excerpt from GameRant's article on the denial (Source:
https://gamerant.com/baldurs-gate-3-development-rumor/):
Following the online hearsay about Baldur's Gate 3 being developed by the Divinity: Original Sin team, Larian Studios went on to deny the rumor, and then added that it hasn't even bought any IP. As stated by the Belgian developer, it is going to continue to work on Divinity, as well as its recently announced project code named "Gustav", which the studio will officially reveal once it's good and ready to do so.
I'm not sure your denial actually implied that but I'm having a hard time digging it up. I might try again later.