No tut, thats what I originally thought when I saw it used in a match and that confused me. Go test it if you cba.
If a defender runs back through the tele at any time in the map it then becomes 2 way active, that will never turn off. Until they run though it back to their spawn then its not active.
Its nothing to do with going through the tele at the same time as an defender, that I would consider a big bug and not something I was even aware of being easily done I thought it was a one off bug that happens occasionally, not only that but you could use that on any map to finish it if that were the case.
Although im slightly confused, this tele always has a blue glow whether active or not, you cant tell so im not sure which one you are talking about. This is the tele in the bunker with rox and sniper next to sniper nest, not the main gate one btw.
I will test it, it worked the way i explained when i tried it last. However, it was quite a while ago and i dunno if it might have been changed due to fixes or leagueassault updates. Anyway, i´ll answer l8er when i tried.