Wow, this is a crazy-powerful agenda if scored.
The question is, will anyone bother to use it?
2/4 agendas often have some pretty cool effects. (Nisei MK II, for example, singlehandedly enabled a lot of Jinteki glacier builds.) This is probably at around the same power level, but it's less clear how it will fit into a deck.
The problem is that NBN has a lot of really good agendas already, and this has to compete with all of them. AstroScript Pilot Program is almost an auto-include, even if it's limited to one-per-deck. Project Beale is really solid, just because 3/2 agendas are precious. And Explode-a-palooza is really popular, because of it's "consolation prize" of 5 when stolen.
So where does that leave Net Quarantine?
"Mostly unused", most likely. But for a deck specialized around traces, it has the potential to be crushing for runners.
High link runners are becoming a lot more commonplace. Security Nexus gives runners a reason to build link, even if they're not in a trace-heavy meta. Being able to zero out their link is a big deal, even if it is only for the first trace of the run.
The second ability though, is where Net Quarantine really kicks things up. However much the runner spends to increase their link, you get half of it back. This makes it a LOT easier to justify spending money on traces. And if you have more than one Net Quarantine scored, (or copied via Media Blitz) this effect stacks, so you could potentially be earning back 150% of your trace investment, which is kind of bonkers. (Eat your heart out, Power Tap!)
I don't think that this card will see widespread play, but I think it has the potential to really re-enable trace-heavy decks, even in an environment where 5-link runners are not unheard of.
For bonus points, combine with Surveillance Sweep.