Someone who is a member of the government cannot restrict access to a public forum, due to the First amendment. However, a private company are allowed to do so, and often communications that would constitute a public forum are done in spaces owned by private individuals or companies rather then the government. So for instance Trump's Twitter account was a public forum which limited Trump's ability to ban people from it despite Twitter, as a private entity, still being able to ban anyone they saw fit.
This suggests a potential way for a government official to indirectly control who can participate in a supposedly public discussion by picking a venue that is controlled by a private entity that is likely to ban dissenters.
So for example a government official renting space for a debate on gun laws from an NRA owned facility might reasonable expect the NRA owners to evict vocal gun control advocates from their building without having to explicitly request it. As another example presume Trump became president again and started using his Truth Social account the same way he used to use his Twitter account. He would not be allowed to ban dissenters from his account directly, but it's likely whoever manages moderation of Truth social would ban Trump dissenters anyway.
Is there any law or precedent that would restrict this sort of indirect banning of participation in a public forum via careful selection of where the forum is held?
