The Tiberium ore from that mod does not have a config, The ore itself is called TibGrowthNode, and seems to behave different from standard ore (spreading, etc.)

I took a look at the mod and I don't think it will work with RSO correctly. Ore that it spawns is not actual ore - it's just fake nodes. And since RSO breaks some base game rules a bit when spawning ore (can go outside chunk that is processed) it will not with this mod properly.
I can add it's fake ore node to ignore list in RSO so it will allow it to be spawned freely using normal rules.

That would work fine. Given its nature as a 'spreading' ore, just having it in-game is enough to get things rolling.

Could you elaborate on how to do this myself, or is it not an easy fix? My group is holding up starting a new game due to this.

I needed to check myself first - I added the ignores and released a new version.
There are some errors from tiberium mod when you generate the map - they are there regardless of RSO presence so I guess it's a problem with tiberium mod itself.