> and because an open source search engine will be tricked by all kind of nasty SEO Experts and it will be very hard to promote actually good Content.
FWIW I suspect that would be the opposite, because if it was free software then you would end up with many forks of the code that decides how to prioritize results, which would multiply the effort required by SEO spammers to target you. Meanwhile you would start with far fewer users and be that much less of a worthwhile target for that reason. And by the time you're big enough to be worth targeting, you have the resources to spend addressing it.
FWIW I suspect that would be the opposite, because if it was free software then you would end up with many forks of the code that decides how to prioritize results, which would multiply the effort required by SEO spammers to target you. Meanwhile you would start with far fewer users and be that much less of a worthwhile target for that reason. And by the time you're big enough to be worth targeting, you have the resources to spend addressing it.