I said "it's not completely impossible." Just like it's not completely impossible the Phillies trade Velasquez. Presumably the Phillies were most willing to step up and exercise the option, while other teams probably bluffed, hoping the Astros would not pick it up and they could get him for nothing.
I'm sure, if he performs, Neshek will be more valuable in July, when he'll have less money left (which the Phillies can just pay) and teams' are clamoring for relief help. And he has value pitching for the Phillies. But if some team's set-up guy went down with an injury in March, or Klentak was in talks about another deal and a GM expressed interest, ya never know.