Then the words to use are:

Lightning network is a technology that permits bitcoin to scale. This enables us to have most deposits and withdrawals occur promptly and at nearly no cost.

That's all that's needed from a Robin Hood / exchange to say about it.

If someone says "What about ... mining" or whatever, well then you go into further details.

Robin Hood was trying to score points, and whomever wrote and whomever approved that blog post, well they were uninformed about that which they were writing and publishing.