What, may I ask, is pre-ZSG timeskip and MU garbage?
Pre-ZSG (Zero Sum Game) timeskip refers to the jump of some five or so years between The Soul Key and Zero Sum Game and also Rough Beasts of Empire which are both Typhon Pact novels and the latter takes place entirely before the former and allows Deep Space Nine stories to be told during the post Destiny Era.
As for MU Garbage. S/he it seems has a problem with the fact that Warpath/Fearful Symmertary and The Soul Key aswell as a few novellas and short stories focus on the Mirror Universe from Deep Space Nine.
I hope that helped.