Checking claim in paper "A Read-Only Transaction Anomaly Under Snapshot Isolation" by Alan Fekete et al
The claim in the paper is true (I never doubt about it, but just wanted to know why) because only the dependencies between the reads and writes of concurrent transactions determine if these are serializable, but not their commits (nor their aborts, obviously).

In the example above, extracted from the paper's claim, the fact that PostgreSQL aborts T2 has nothing to do with serializability between T1 and T2, but only with some design decision in PostgreSQL that I ignore (if someone knows I, please write a comment to this answer).