Three things:

Read somewhere this week that LP are relaunching/trying to build profile/share etc and this may be part of that.

I don't think Tesco will care that people are queuing up to spend £25 a bottle on multiple Champage purchases! Their good wine offers always sell out anyway.

And any one who can make money buying and then resellling Champagne at that price is someone Tesco should want to emply, not stop!