Hmm @andrei handled that, supposedly “forever” was an item in the list, just like it is for suspensions – is it not? Did you scroll down? Perhaps we missed that item in the to-do list for the feature.
In the meantime, you can simply set it very far in the future. I don’t really see a problem here. You have the ability to do what you need to do. Set it to 2050. If your forum is around in 2050, then you can worry about it at that time 