I suppose Pash was making the distinction between simply having to fight vast numbers of TIEs (?deadly?) and fighting vast numbers of TIEs while Imperial starships take potshots at you with turbolaser bolts as big as your fighter (?really deadly?). Han is going to cover the retreat of the fleet (cruisers, corvettes, gunships, squadrons of starfighters) with the Falcon (modified light transport)... I suppose he might be hoping they would concentrate on capturing him and ignore the other ships. Rather like his tactic in Tatooine Ghost but rather than the Falcon dumping a canister with a bribe it would be the Falcon acting the part of the ?canister?. Personally I think Han had been able to ?break into? the conversation because as Commanding Officer of the operation he would have all squadron frequencies available so he could order squadrons individually, and knew he needed to switch to that frequency because as Wedge?s friend he knew what Wedge?s reaction would be.