Imagine these two scenarios...
A. Kill or be killed. Press the button to save yourself and get to choose to evict someone else
B. Kill or be killed. Press the button to save yourself and get to choose to evict someone else... but also win £20,000.
I'm sure nobody would have a problem with any HM opting for A, it'd be the sensible option... so why would the addition of a 20 grand reward make the same decision wrong ?
Jason did the right thing... well played.