How do!

Quick question based off what I consider to be a ropey ruling.

So, there were my Rhinox cavalry, merrily beating seven shades of snot out of my opponents main unit. Second round I stomp them good, reducing their second rank to 4 dudes. Hurrah I thought, they're no longer steadfast, and staring down a break test at -lots.

Then my opponent claims that on account I don't have a rank myself (third Rhinox literally fell foul of a pit of shades) but he still has has front rank, he remains steadfast, and would remain so until all but four of his dudes were splutchy little pancakes.

Rule book isn't clear on this, but a single rank, by the dictionary definition is in fact just a line. You need multiple lines to call them ranks.

Now as I said, rule book isn't clear, therefore both of us were being rules lawyers. I now want a consensus of opinion on the matter.

Can you really claim steadfast, based solely on your front rank or not?