I think the whole "reaction" thing isn't really an issue, or if it is it comes way down the list behind the following to make you a good player:
1. knowing the map
2. knowing where the good bits are to get cover and/or vantage point
3. knowing where the filter points are
4. knowing where the starting spawn points are, and where people are likely to move to from there (and then intercepting them)
5. once you have killed from, if the person is going to come back for you, knowing where to stand so you can see where he is coming
I would also say, as someone who used a silencer, it is also my main strategy to get as far away from my team as possible and get behind enemy lines, quite often I can take down 4 or 5 people at close-ish range before they know where it is coming from.