I think ipb should have something when you view a members posts and topics that the quick search is capitable with it

Can't you do that already by clicking on the member's name and selecting "Find Member's Topics" or "Find Member's Posts"?

I mean searching those posts

You can. Go to search, type what you are looking for, then for author choose the member who's posts you want to search in.

I mean searching those posts

Hasn't your browser got that search function? Ctrl+F

It does but it seems easier..

What could be easier than clicking the search link at the topic of every page and typing the person's name in the author field and the "search" you want to do in their posts?