The problem is that there are two competing precedents, with different outcomes.
Precedent 1: Joshua B, which says "When your turn begins, you may gain . If you do, take 1 tag when this turn ends." The argument is that the conditional ability is optional (sort of like a paid ability) and that the whole thing starts when it's triggered, and the second sentence resolves even if the card is trashed in between. Note that the second sentence begins with "If you do," (In fact, FFG's official answer calls out the phrase "if you do" as the thing that makes the second sentence part of the first conditional ability.)
Precedent 2: Breaking News, which says "When you score Breaking News, give the Runner 2 tags. /
When the turn on which you scored Breaking News ends, the Runner loses 2 tags." This is also a conditional ability, but you don't have a choice about whether to do it or not. But the second sentence, which has a new evaluation and a new condition, "when the turn ... ends" has been ruled a separate ability that is evaluated and resolved at a different time than the first ability.
Sensor Net Activation lands right between these two. It's optional, and its two sentences are not separated by a line break. But the second sentence has a new conditional trigger, and is worded with the same "When the turn ends" format as Breaking News (Implying it is evaluated and resolved at that time). Also, agendas have the added rule that their text box is blank when they're in the runner's score area. So the Joshua B ruling, which applies to a resource that has been trashed, may in fact be different than Sensor Net's effect if it is swapped or forfeited.
If they took out the line break in Breaking News but didn't revise the ruling about how it worked, that, to me, would be an argument that Sensor Net functions the same way, since both are agendas. To me it's absolutely reasonable that a player who knows the Breaking News / Exchange trick but doesn't know the Joshua B ruling would think Sensor Net functions this way, and I think a ruling is needed to clear this up.