This is mere sophistry and the phrase does not mean what you think it means. There is no contradiction here.
The phrase is almost always used when comparing/contrasting different schools of philosophies/religions to emphasize that while within the worldview proposed by each of them they may posit absolute truths, outside of their framework there is nothing i.e. the phrase itself has no meaning. There are two different frames of reference at play here.
James Tartaglia in his book (referenced in my other comment here: https://news.ycombinator.com/item?id=32920232) points out that our inability to make sense of reality from the outside in (i.e. Nihilism/no meaning) does not prevent us from giving meaning to reality from the inside out (i.e. as it is lived via any chosen philosophy/religion). The distinction is very important since it resolves a seeming contradiction i.e. how can life be both meaningless and meaningful at the same time?.