I think the LibDems are undoubtedly being opportunistic. With around 6-8% of the vote currently, they are just trying to tap in to that 48%.
I would have more time for them if they just sat quiet while the current process was carried forward and went to Conference and discussed internally putting it in their next manifesto rather than shooting from the hip like this.
It undermines the democratic process.
They need to be careful though as the polling shows that 30% of LibDem voters also voted to Leave so they risk alienating current supporters.