Depends on the RNG flaw.
If the flaw was simply that 0 was always considered a participant. Then even if a 0 could be rolled, it was a fair distribution for whoever won. With 4 participants, everyone would have gotten a 20% chance, and 20% chance on the 0 (which would only happen in 1/5 cases). Which is most likely the cause and easily allows a reroll for only those affected.
The other RNG flaw would usualy mean a poor RNG implementation, and favoring certain numbers. Sure, that flaw could get numbers like 0, 8, 16 etc (or offsets like 5,13,19) to show up more regularly, and in that case would require a complete reroll server wide to counter unfairness here. But any decent security oriented RNG would already be fine (sure, they can have minor advantages, but practicaly this would require millions of participants to show). And those RNGs are most of the time already available by default within software. Its unlikely this was the cause.
