They took it further because Derek hasn't had time to copy it yet. The Murphy doesn't do anything that someone else hasn't already suggested, written, or discovered.
You must be someone that cheats and offended by what MI does. Let's get perspective:
The 'impossible 5km split' crucial to the DQ only became evident due to Derek's hi res pics of him at 18.7km, Derek actually being the first to correspond with FM about that stoppage, then the time taken from re-entry to the 20km mat.
There were also other hi res pics identifying FM at other stoppage points and evidence of real running pace to the next mats.
This is the crucial evidence that LAM then followed up with requesting CC TV footage from retailers in the area, talking to bystanders or marshals etc, because LAM is able to access that info.
This most likely gave them evidence of a larger stoppage break, so that they could be absolutely certain he could not have run that segment.