Cause Dach will get around the same as LEhkonen was having, that's the price fro a players like that, was playing 18:00 minutres a game last year,....2.8M for 2-3 years.
As for cap space.....well, that's what Hughes said like 1000 times since he's here, he's the ones prioritizing it and you don't clear it when you need it, you clear it as soon as you have the chance cause that's not just money, that's also players taking away a spot for a younger players that needs to develop also.
Lehkonen had proven himself a lot more then Dach has done so far. All Dach has going for him negotiation wise is his potential from what he did in the WHL because being outplayed for 18min on a bad team isn't impressive.
As for cap space, Hughes has not actually prioritized it. If cap space was a priority we would have done a McDonagh like trade with Petry instead of acquiring a replacement that's almost as expensive. Same with Weber, we didn't prioritize cap space in that deal which is why instead of clearing a lot of space we only saved a few million.
Yes if you have the opportunity to get rid of bad cap at little/no cost you do it, but if clearing cap as you want was a priority we would be willing to pay for that and Hughes' actions so far have made it clear we aren't willing to do that. Instead the focus is on building where contrary to your "take a spot from a young player" narrative actually requires veterans to insulate the young guys, which is what Hughes said many times when talking about trading Petry. He always said he wanted a replacement veteran D, either as part of the trade or being acquired some other way to insulate the young D and if he couldn't get that replacement he would keep Petry. That clearly shows clearly his priority was about clearing cap space.
Bergevin left us in a crappy position cap wise, but when you aren't competing it doesn't really matter because with patience it fixes itself. 17m next summer, another 7m in '24 and '25. And likely another 10m from Price. Cap space simply isn't the priority, it's a nice to have.