I feel like people really don't understand what these specific signals are for. In our current setup these are only to give priority to a transit vehicle that is waiting. That vehicle therefore needs to be at the front of a queue, or its own dedicated lane (and therefore no queue). On areas of king with mixed traffic the only use for these would be to hold all over movements while a streetcar makes a turn, less priority and more just a safe phase; on areas with dedicated lanes you'd also generally only use these for a turning movement, as there shouldn't be any conflicting movements for through streetcars you can just use a standard green.
They can be used for through movements when buses have a queue jump lane, to get ahead of waiting cars. There are some rare scenarios where you might warrant two opposing phases (a queue jump through lane facing a queue jump left turn lane), and there doesn't seem to be anything preventing that in the regulations/manual. On King, under our current regs, you would likely just use our signed transit signals, as is the practice on all LRT lines save Ion.