I think you are probably correct in the fact that the guest running in the BUCS relay is a difficult issue, and some teams will get an advantage from the guest runner. It was certainly the case at BUCS in 2015 from my memory. However, I think you're letting your emotions rule over you slightly.
On the gaffling, of the two teams Shuoc lost to who I ran near, only Paul had one similar gaffle to me on the whole course - on the first control, and after that we had different forkings; Jack had no similar forkings for the entire course (so if they were following me then they lost their teams time by not taking the optimum routes - i.e. if Jack hadn't come up to our #8 after punching his EUOC could have won, though I am guessing that from the gps I'm not sure what he exactly did). After the first gaffle, you and I actually had the most similar combinations. Sadly it just seems luck of the draw on this one.
I intentionally didn't push the pace once I saw how the race was shaking out, as I didn't want to drag any teams through because of my running, which I do think happened, but maybe that isn't enough and I should have pulled aside at spectator? Perhaps the easiest thing is to not have guest teams involved? Interested to see what everyone thinks.