But this isn't just a sad case of political opportunism from Home Secretary Amber Rudd (after all, her boss Theresa May has been after Whatsapp and Snapchat since 2015) - it's also a hopelessly ineffective tactic.
Masood may well have sent a message shortly before his attack. But even the security services had had access to Whatsapp, are we really to believe that they would have had the capacity to zero in on this one fateful drop in the ocean of messages constantly being sent and delivered, then to brief and dispatch officers to its exact location, all within the couple of minutes between message and attack? It's impossible.
More likely they would like to look at his messages retrospectively - to learn more about his contacts in the terrorist world.
This is a more reasonable aim. But still not one, I would argue, that's worth giving up the rights the rest of us have to communicate in private.
The Prime Minister and Home Secretary should be asking themselves what exactly it is they are trying to protect from these terrorists, if not the basic freedoms of their citizens?
They would likely argue that if we've done nothing wrong, we have nothing to hide - and should therefore be more than happy for the government to snoop in on our messages.
(Honestly, if the Government were ever to tap into my Whatsapp chats, I'm sure they'd likely be bored to tears by the endless inane yammering.)
But that's not the point. Private citizens who have indeed done nothing wrong have the right to say and do as they please without interference by Amber Rudd or her friends at MI5.
And further - if we were to open up Whatsapp's encryption to the security services, we'd be creating a back door for hackers everywhere and therefore likely leaving millions open to blackmail over perfectly legal messages (ever sent a saucy photo to your other half, for example?).
This is an issue I'm not even sure Rudd fully understands.
And anyway, Whatsapp don't have a monopoly on encryption. Surely if it became an open platform for MI5 to dip into whenever, the terrorists would just switch to messaging on a new app?
It's a game of cat and mouse that nobody will ever win. The fight against terror won't be decided by phone encryption - it's so much bigger and more complicated than that.
So while that war still rages, we need to remain clear-headed about where our red lines are.
A huge media storm and slew of reactionary legislation sounds to me like exactly the sort of thing that would encourage more terrorists. If we allow this one evil attack to curtail the freedom of the rest of us, we're effectively holding our hands up in defeat.
After all the Government talk of carrying on and not letting this attack change anything - this kind of invasion into the privacy of the public would represent the exact opposite.
Masood was an evil murderer - let's not allow him to do any more damage.
This blog post first appeared on Social Schmocial.
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