TSLRCM tries to fix to the best of our abilities the issues The Sith Lords had due to being rushed. Containing a host of restored content and fixes many bugs left inside TSL giving you the most polished and best possible chance to get the full experience.
You might have seen this main menu before. Maybe you even tried one of the mods that "restores" it. Wonder why say "restore" with quotation marks?
That's because so far I haven't run into a mod that doesn't simply replaces Nihilus screen with this (which is silly). Of course this woulnd't be the RESTORATION MOD (and I would be doing a really sloppy job) if we just implented as such instead of according to Obsidian's original design.
So you have to meet requirements set by OE for this screen to appear even when using TSLRCM 1.8. Wonder why it didn't show then in vanilla? Because the script broke leaving you with Sion instead (maybe you already know the requirement now?).
I am surely not going to tell what you need, you still have some time to doctor it out ;).