I've been trapped in the culture ui multiple games with only disabled traits affordable with my culturepoints.  In the interest of avoiding that, I put together a little hackish fix to avoid the problem here

• Culturetraitdefs.xml modified so that all Disabled true traits have a cost of 999, this was done to hopefully prevent getting cornered with a disabled trait that cannot be unlocked as the only option
• CultureTreeDefs.xml was modified to set the number of required traits to move to the next tier to be equal to that of the non-disabled techs in the tier before it when disabled traits are in the previous tier. This hopefully prevents getting cornered with a disabled trait as your only option... although with 999 as the cost for those, I don't expect that happening
• No other changes were made to these two files