Blue-responsive cones' responsiveness does drop to effectively nothing at frequencies too high to be called "red". The limit is more of a yellowish green. Red-responsive cones do, however, have a response well into "blue frequencies". So a blue laser could stimulate red-receptive cones even though a red laser couldn't stimulate blue-receptive ones.

BTW, although it's not really an answer to a specific question in this thread: reptiles & birds have four kinds of cones, more evenly spaced than ours (as opposed to the way our green and red are crowded together), and no rods. It's one of the reasons why evolutionary biologists think the common ancestor of mammals had spent a long time evolving heavy specialization for a nocturnal lifestyle.