That's just how Steam bundles work. It decreases the cost by the undiscounted price of the parts you own to some minimum (I think it's £1). Most likely they only thought as far as bundling the Rebuild edition and SnowRunner and giving it a cost of £60 and didn't consider this.
Or maybe they did it deliberately given the name. Who knows
Mainstream betting has already gone too far even within the betting laws. There is no way to do it responsibly