Consider history, for years Cooke was the only really world calss rider capable of the wins. Therefore she was the protected rider, and always very single minded. Now time has moved on, her tactics remain the same, are more predictable, and others know how to counter them. The new generation of riders is very talented, and quite possibly LA is the best of the bunch right now. Also you could ask why when Cooke was Wiorld and Olympic champion, there was no team place for her the following season in a mjor team?
the situation is difficult, and a ral management problem, whoever is going best with the best chance should be protected (and it's only 5 riders per team). The management have to be firm and plan, but once the race is on, then what happens, happens. It appears that Cooke is not the most popular, to say the least, amongst the other GB riders, and it could result in a 4+1 team if the decision is to protect LA.
Maybe it all goes back to the Nationals, where she has had a good working over from the Garmin-Cervelo riders and didn't like it one bit.