Can seizures be a sign of alcohol poisoning if someone is really drunk?

Yes : Seizure can be a sign of acute alcohol intoxication. This is more likely to be seen in the young novice drinkers who underestimate the power of this neurotoxin (brain poison). Seizure can also be a sign of alcohol withdrawal. Both are bad and require emergency medical care.

Seizure from alcohol: Yes. Alcohol intoxication lowers seizure threshold.