The problem isn't that the page contains non-free things on it. Or even that the free mini-courses require registration. The problem is the post had a link with a referral id in it.
There is little doubt in my mind that those free mini-courses would be interesting and helpful to other members.
IMHO if you can start a thread without a link with a referral id in it, you should.
In any case, I've sent a PM to the Administrator, so things should be cleared up soon.