Dubas put together a better team and it is extremely impressive that he managed to do so without it costing much additional cap space - but he cleared up zero dollars for Marner.
Before his moves:
C: Tavares, Matthews, Kadri, Gauthier (27.8M)
LW: Marleau, Hyman, Petan (or some equivalent), Mikheyev (10.2M)
RW: Marner's spot, Nylander, Moore, some random 4th liner (8.48M)
D: Rielly, Muzzin, Zaitsev, Dermott, 2 3rd pairers paid around what Marincin and Holl get (15.8M)
G: Freddie, Hutch (5.7M)
Two spares, plus Kessel retention (2.6M)
Total 70.58M with Marner still to sign.
After his moves:
C: Tavares, Matthews, Kefoot, Spezza (26.8M)
LW: Johnsson, Hyman, Petan (or some equivalent), Mikheyev (7.35M)
RW: Marner's spot, Nylander, Kapanen, Moore (10.94M)
D: Rielly, Muzzin, Barrie, Ceci, Dermott, 1 3rd pairing guy paid around what Marincin and Holl get (17.81M)
G: Freddie, Hutch (5.7M)
Two spares, plus Kessel retention (2.6M)
Total 71.2M with Marner still to sign.
Despite the fetishization around here that every move was made to free up money for Marner, the moves were made to build a better team around their core. It had nothing to do with freeing up money for Marner, and indeed no money was freed up for that.