Note in that table density refers to ball size, not component placement, although both are linked to courtyard. Part 6 discusses component density and rework considerations (too long to quote).
I guess that the guidelines were designed with large BGAs with many balls in mind, rather than CSP type packages which are much smaller and have few balls.
My guess is that if you use CSP package, you are really wanting a high component density and don't care so much about rework (e.g. high volume consumer products) (otherwise use QFN/QFP). With BGA, the large number of connections really dictates the need for BGA package, an 1184 pin QFP is not at all practical. However, I didn't see any guidance related to low ball-count BGAs or CSP specifically.