But it cues your brain that it might not be safe to turn left.

Not quite. Yellow blinking left arrows are always for a protected left turn lane. So when blinking, it does become more like an unprotected 'turn left on green' type of light, but you don't have the straight-through traffic coming up behind you, since you're on a dedicated turn lane. And the yellow flashing arrow is usually timed so that it happens at the safest time to make an unprotected left.