I think it's fine; not everything needs to keep growing forever.
Nothing physical can keep growing forever.
Except, maybe, the universe itself?
I considered that before posting, but think I'm safe: just don't ask for a rigorous proof!
is "unit sales" number the only number in the report?
Of course not. Nobody is saying that revenue is stagnant. Only iPhone sales are. It seems correct to me.
it is also correct to say unit sales are stable. using a word with negative connotation to describe a largely positive event smells bias and manipulation to me.