2 Tablespoons of rum in a cake batter. The cake will probably serve 10-12 or more people. JMHO, but I don't see a problem with it. It would be an entirely different proposition if for example, you had a fruitcake that had been swimming in bourbon (post-baking) for a couple of months. I would have a problem with that.
Could you substitute a rum extract? ....sold near the vanilla extract.
FWIW, I worked in public libraries for decades and we just.didn't.imbibe, rather an unwritten rule. Not only for the risk of offending library patrons, but quite often at our potlucks, we had young workers under the age of 21.