The statement just mentions C#. Java is amazing and fast in capable hands, but so is C#. Of course you can have problems with a stack, but that's nothing to do with the stack in this case, but rather a skill problem associated with that stack.

If my current employer started having new software written in C instead of Java today, and while C has many problems, the problems we'd have would be all self-inflicted skill issues, not a direct problem with C.