Almost certainly still underground in Germany with plans to leave for Italy and Argentina. It's not very likely that he'd take off to Egypt to agitate and then scoot off to South America.
It would have taken time to establish himself there. And really, did Arabs need his help to do whatever it was they did in Egypt in 1948? What was the necessary special contribution an ex-Nazi would have made?
But of course, at the time, nobody knew where Eichmann was, so all kinds of rumors could circulate. I'm not aware, though, that anybody has authoritatively corroborated your rumor in all the years since Eichmann was captured and put on trial.
Thanks x.