The way I read your comment the whole reasoning appears to be off.

Let’s assume I have a technical trading system that makes real good money. Sharing the system will lead to either

a) everybody buying when I want to buy. Driving my price up and my gains down. Or,

b) I will sell my previously bought assets on the way up. This is where a lot more can be earned then by stopping people out, in my humble opinion.

My trading is not affected by unusual moves in IG’s quotes. If I thought so, I’d be gone.