Itīs 2-5 in second set tiebreak here, nothing impossible to come back. If it would be Pashanski for example then OK, but does Gaba have such a history?
There have been several serious injuries (mostly knee or ankle related) on scorelines like 6-0, 1-0 lead(!), in the very late stages of third set or even at opponentīs MP so there is such a possibilty and Gaba actually had pretty serious problems not that long ago. We will see when he will play his next match.
He was 2 points away from losing, not much worse than retiring at match point. And yes, he does have a (small) history for this, like 2007 Roland Garros vs. Cipolla L 6-7(6), 3-6, 2-5 RET