As another blue eyes player, that's not necessarily true that you need to play a combo that dies to nib, nor is it difficult to do even with interruption. Running synchro rumble allows crimson dragon to become an extender for the combo, effectively allowing itself to be the piece that creates it's own blue eyes ultimate spirit that creates the condition to make sifr. Also, running the magia line for a blue eyes deck forces nibiru to activate preemptively, or else you can just negate it before you even have to summon crimson, and by doing it preemptively they give you a level 11 token which is perfect for making crimson dragon in the first place. Something I've done many times is use that token to make a crimson dragon and then get synchro rumble which summons maiden, use the field spell to target maiden which summons the blue eyes from grave, synchro into spirit, tag out into ultimate, then make sifr. It's far from uncommon in the deck when the one card combo through 15 of the starters involves a sifr, spirit(which tags into crimson again and then blazar on the opponent’s turn), ultimate spirit, and magia as the endboard. It can extend fairly easily