All constituions have a limit to freedom of speech and the example most often given is 'dont cry fire in a crowded Cinema Hall", that isnt counted as Freedom of speech.
If you read the velow sitation it comes close to this limitation.
At the time of the police arresting the two girls, the city and the state was absolutely on verge of a calamity of a riot if in case someone were to do any kind of mischief like burst a firecracker etc and it were to be taken as a celebrating the death of a popular leader That is the reason they had 40 thousand cops on the street in Mumbai alone and virtually every major city was shutdown in the state for protection
So it is natural the cops came down hard in this situation and there was a valid justification to it
Contrast that with two state sponsored events such as
1. Mamata Bannerji had someone criticizing her put behind bars
2.Chidambaram had someone arrested for criticizing his son to be corrupt.
Which clearly demonstrates the government curbing dissent and freedom of speech
If thinking were to be straight I would expect pom-pom carriers for Freedom of speech would be condemning the police in the Mamata/Chidambaram case and applauding them in the Mumbai case
But in reality they are mute in the Mamata/Chidambaram situation but very vocal in the Mumbai situation because it is obvious they are not really concerned about freedom of speech but just like any common partisan hack like a Digvijay Singh.