Triathlon GB made this race a non-qualifer the morning of the race. (Run was shortened to 5k, that's another story)
The only way for a GB athlete to qualify was if Vicky Holland (2016 Bronze medalist) won the race. Any other results would result in no GB athletes auto qualifying.
This race is literally a TEST event. There is no prize money and there are no points for the yearly series (which also has prize money)
As a result, Taylor-Brown and Learmouth were racing to prove to selectors that they were capable of racing on the course. They were running side-by-side easily in first. They demolished the race. They are training partners. They are roommates on the road. First or second held no baring as they both showed they are capable of medaling at the Olympics and beating the rest of the field.
No other country had their Olympic selection altered as a result of the placings.
Ex: USA's Summer Rappaport finish 7th. And she moved up to 5th after the DQ's. She needed a top 8 to qualify.
Ex: Vicky Holland needed to win to qualify. She moved from 5th to 3rd. Still did not qualify.
Literally every athlete that did/didn't qualify was not effected by the ruling.
This basically never happens in triathlon. Especially in ITU.
The rare combo of the race being shortened, two training partners racing for no money, no points, no guaranteed selection, and clearly besting the rest of the field lead to this outcome.
Not a great look for triathlon to DQ them. But also, not a great look to have an Olympic test event end in a tie. Hard to fault the girls. They were celebrating stomping the rest of the wold in. Together. They certainly proved they are the top of the heap.
Hope that helps explain what happened.