First, perhaps not. In that case, the budget airline mindset kicks in: if some people are willing to pay for something, charge differentially.

However, I wouldn't be so sure that £10 per user isn't the actual value of the ad impressions and data. Users who would pay to opt out of ads aren't a random sample. They're adblock using airline ticket buyers who paid for some sort of premium experience. Could easily be a premium segment.

Advertising is valuable, and that value isn't evenly distributed at all.