He didn't do it to Nylander. They signed Nylander to the exact contract he wanted (more than all of his comparables, including players that were better than him). The cap hit was low because the deal was signed 5 minutes before the deadline. In year 1 of the deal (the final year of Matthews and Marner's ELCs) his cap hit was 10.28 million. The Leafs folded, Dumbass even admitted it.
They followed it up by handing Matthews that garbage contract.
Eichel: 10x8
McDavid: 12.5x8
Matthews: 11.634x5
No public negotiations, no media warfare. Just one random day they announced it. And now with McDavid and Eichel still on their old deals, Matthews is somehow the highest paid player in the league. But it doesn't stop there, when McDavid signs his next deal making him the highest paid player in the league, guess who needs another extension making him #1 again?
What type of deal is Marner expected to sign after they folded on Nylander, and then just gifted Matthews that joke of an overpayment? Nobody else thought about the team, not even the management. They even gave players away to make room. But now Marner's the bad guy for not being a team guy.

They're all going to the bank and sleeping well at night as they lose to underdogs, zamboni drivers, and get blown out in pivotal playoff games at home on Hockey Night in Canada after Bob Cole's death.