Pensions don't automatically split 50/50 on a MFS return for community property states because they are sometimes considered separate property. See IRS Pub 555:

Pensions are classified as community or separate depending on the period of participation in the pension during the registered domestic partnership and whether domiciled in a community property state or in a noncommunity property state during the total period of participation in the pension. Distributions from IRAs are deemed as separate property.