It looks to me like there is a misunderstanding add to the purpose of the siyum. There are this, especially campus, who make a siyum during the 9 days and then eat meat since it is a seudas mitzvah. This is a somewhat controversial practice and I cannot imagine that any authority would hold that this online siyum would suffice since it would not make what I eat at home a seudas mitzvah. I think that this is what those who think this is a bad joke understood the purpose to be. It seems that the there is a Chabad minhag to have a siyum during the 9 days without eating meat. I guess that this can suffice for that.