I disagree with much of the American interpretation of ‘religious liberty’.
Of course though, no one should be forced to visit a place of worship against their will. Neither should such visits be a regular occurrence, unless of course such a practise is an integral part of the school culture in which case the culture was known beforehand,
I don’t believe this is the case here though.
I would think if the school culture is not explicitly Christian and the Church visit is not a regular visit then the sensible outcome is just for the Muslim family not attend that function.
Similarly if a function was in a mosque then a Christian family would have the option of not attending.
The problem is when the government says that in order to be neutral, there should be no visits. This is obviously not neutral but in favour of the removal of God from society which is strongly favoured by a sub section of the populace.