Intended. Mori wasn't ever christian, after all S2R+ has 'realism' in its title.
However, no problem to make Mori's ships accessable if they are christian, will be done in next release (2.97.3).
Else, i suggest you don't convert to christianity liberately with factions which weren't ever christian ( all, except Otomo ;) ), so perhaps consider to convert back to buddhism within your Mori campaign, as said it's not clever. Christianity is balanced for Otomo alone and else only as disturbing factor for all factions for the regional unrest/repression aspects.
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