The court is plain silly if it's concluding that multi-billion-dollar deals create resistance or diminishes incentives. If anything, it creates incentives by proving that another search engine could make billions from smartphone fees alone.
It’s an exclusive deal that prevents anyone else from offering a similar deal. Of course it reduces competition. The only question is whether it also violates the monopoly law.
I’d encourage you to read the decision, I just pulled two paragraphs from a pretty exhaustive document.
I highly encourage you to read about monopolies and their mechanisms. Competitors can be incentivized with a monopoly's profits all they want, the amount of money it'd take to enter the space is unfeasible.
They're saying that if Google is willing to pay so much to be the default that there's positive ROI that another search engine could tap given the up-front investment to buy the spot.