A friend said "omfg" over text, is this kufr?

i've heard that saying omg isnt haram as "God" isnt one of the names of Allah, but what about omfg?

We are not sure if your friend was awere whst he was saying and in which state was he, but that vulgar exclamation of belitteling God with swearing is sure a sign of great kufr and something very dark and a great dhulm. Best to find other friends. OMG could be considered as a dua exclamation, calling on God and not that it is not wrong, but it is even recommended.

when confronted about it he said that he heard as god isnt one if the names of allah, it wasnt kufr, would they be excused due to ignorance in this case?

It is a very irrational justification as God means Allah in Arabic and everyone, jews and christians speaking Arabic call God Allah.When said God, in almost every culture it is meant the one and only God, so Allah.Depending where he lives, does he practice, upbringing, is he under psychological or spiritual maladies, maybe he can not reaaon that out.

All I can say is that he was unaware of it constituting kufr and apostasy from Islam, and merely viewed it the same as saying Omg or oh my god.