Well first of all lets condemn these pages first. I assume no one would defend these pages right? Agreed that this is not liberal thought?
If you agree on aforesaid then lets move on to whether the missing persons have any role in this. Now everyone knows a common man does not have enough IT know how to trace an IP address and that too which is expertly changed bef it could be traced so asking if you have proof is useless. You can make a personal assessment on checking the normal twitter accounts of these persons and whether they could have done it but certainly you cannot prove it.
The law enforcement agencies, decided to pick these people up(if they did, not proved). Now it would have worked too if they were arrested under incitement to violence or even Cyber crime and produced in front of court. Agencies however picked them up, that tells me two things either they thought evidence won't hold up at court or the hue and cry the moombatti brigade will make will turn this to humanitarian issue(least likely scenario) . Second there was a lot going on than just some blasphemous pages. Quite honestly agencies don't pick up for blasphemy or even criticism of Army or state otherwise whole Dawn News staff would have been missing. They do if organised anti state psy war with money trail is found. They pick up to investigate and round up the whole op as an intelligence op and they certainly can pick up people for that as premier counter esp.
If the agencies picked up for Blasphemy and mocking Army it is an overkill. If they did for latter it is fully justified provided they gain enough evidence to support the claim.