Re: "right to freedom of expression"
At the risk of being a pedant, a government cannot grant rights.
Quite the opposite, ALL civil rights are granted by government.
An interesting corollary of this fact is that only a government can take your rights away. The reason why this is interesting is that those same governments do like to make statements like "this act of terror is an attack on this or that right". Yet, it is entirely up to the government itself to either retain the right in question or curtail or revoke it altogether. No terrorist can technically do it.
As the result, if a terrorist attack leads to a reduction in our rights - the culprit is the government, not the terrorist. People mostly do not realise or remember that, unfortunately...