People last series kept on saying that people (not just Tom) were only being kept in for their business plans. Then it turned out they were all shite.
Jade was kept in because Lordalan thought she'd done better overall than Azhar (which is debatable, because the edit has buried both of them so hard outside of their PMing stints that it's difficult to tell what either of them did on a week-to-week basis), and that Azhar had poor people skills (which he does - watch episode 2 back - he alienated his entire team, even the people who agreed with him). Also she yelled a lot in the boardroom, which has always been a thing (*spit* Jo Cameron *spit*), so long as you stop when you're told to.
If it were based on this task, she would have got fired, but he's just done firings based on one task only with Jane and Duane and Katie (and of coruse people complained about those as well). He can't always do the same thing, although it's beyond time that at least one Project Manager got fired, and Jade going this week was a better chance than most he's had so far. I'm surprised he didn't go for it. Maybe he's trying to prove a point about it being a good thing to step up and take responsibility but then...it's not as though Jade even did that given that she was forced into the job and was incredibly reluctant to make any decisions at all.