Betsy I'm a tad confused myself (default brain setting most of the time). I wish I could see a picture.
As far as I can work out, standard pegs come out when you have a peiod of lots of little tugs (or one biggun) that cause the hole that the peg is in to stretch out backwards (towards the tent)
oh hell this is hard
So the bit of the peg that is sticking out is being pulled backwards and the bit of the peg that is in the ground is moving forwards. When the hole is big enough the peg just sort of flips out if it gets pulled hard enough.
If you bang a second peg in, at right angles, so its shaft (fnar) is crossing in front of the 1st peg's shaft under the ground, then that will prevent the 1st peg (wot the guy is attached to) from pivoting about and making the hole.
I think that is what they mean.
There is the other sort of cross pegging for doorways wot you have explained in a far more clevererer fashion.
This is why I love the deltas so much, they appeal hugely to my inner angular nerd. I love that the harder the guy pulls on the delta, the harder it pulls itself down into the ground. Brilliant bit of simple engineering. Why Mr Orr hasn't been on Dragon's Den I'll never know.