true. but theres more to the story. its not just if they are entitled to. its if they were likely to. it depends on how far away the person doing the net kill is and if it was possible to follow through if they wanted to. if you did a net kill at full stretch jumping from the behind the serve line, there is little likelyhood that you could follow through with a full racket length, so the oponent is allowed to block the shot closer to the net. if you are already right up against then net and do a net kill, you now have the possibility of following through, so the opponent arguably cannot block so close.
and this is the trouble. there is human judgment involved in deciding if a stoke 'could have' followed through and got blocked.
Yes this is true, angles of possible follow throughs need to be taken into account as well. I.e if the angle meant he would hit the net before reaching opponents racket then no obstruction