Your friend is right and if they did get a downdraft from a microburst they are very lucky and would be a good rationale for being that low.
A microburst is always what drove the Delta L1011 into the ground short of runway in Dallas in summer of 1985. Nothing the crew could do to counteract the downward force.
The technology for detecting has come along way but not every airport has it.
Either way I'm sure everyone is glad the bird safely landed.
