Sorry for the double post, but I don't want to put the whole post into an edit. As for the original issue:
There's a problem with throwing ANYTHING out of the airlock at lightspeed. By the time you push the button to open the airlock, you will have overshot the target by several thousand parsecs because of relativistic time compression.
I can see where you are coming from, I think. From the target point's of view, you are approaching with nearly light speed, and due to time dilation, you do everything very slowly, so you might not be able to press the button in time. Right?
Makes sense, but the problem is that all other kinds of things come into play from the target's point of view, such as length contraction and, I guess most relevant here, also that simultaneity is not invariant in between reference frames (so basically two things happening at the same time from one point of view do not do so from another one with relative speed).
However, things look much simpler in your own frame of reference. From your point of view, it's the target that is approaching you with almost light speed, and where everything is happening very slowly. But in your own ship, everything happens normally. Thus, if you are initially, say, 8 light minutes away from your target, then you have 8 minutes as normal to push the button before the target reaches you.
If you had missed the target by "several thousand parsecs" (i.e. several thousand light years) while you where trying to push the button, then from your own point of view your target just covered several thousand light years of distance within a few seconds. Which doesn't work.
Hope that made some sense. I'm off to bed for today!