Unless he made them scoring . . . then there is almost no reason to move auto cannon dreads up the board.
I think he was worried about Zoanthrope shots, which I did manage to shove under the Reinforced Aegis anyway. I'll suggest that Dreads need to stay in the back.

And supposing a Purifier squad does maul my Gaunt screen, then my Tervigon coughs up a fresh dozen Gaunts, then Prime and Venoms charge your squad. Prime has Shadows, if you passed last time you're due for a miss, Venoms have Lashwhips knocking you down to I1, the Prime gets 5 ID power weapon swings at I6, S6, and WS6, 4 of your 5 remaining go splat and then the Venoms gnaw the last one to pieces. I consolidate back into my Gaunt screen, next turn.

Or at least, that's going by percentages. Even when a dice rolls statistically average, it rarely doles out a precisely average set of numbers each turn. That's why we play the game (well, that and nicely painted bugs look better on top of nicely painted terrain than in a carrying case).