There would be no need for Asobo to “get in trouble” if they had planned ahead for this and had a livery distribution system built into the sim from the beginning. Then they could have just put some words in the EULA for the sim that the user is granting rights to reproduce any models or textures in the Community folder for the purposes of the multiplayer experience.
They could have even included special LOD levels for aircraft makers to used and some encryption system to ensure that the content transferred for MP purposes stayed protected.
By communicating this upfront the aircraft and livery makers would either agree, or not make content for MSFS.
But since there was no plan on how to solve this issue, now I agree it is very difficult to solve, because it would be a big change mid stream.