What is this? ...Pay them 2nd and Aston-Reese to dump Matheson? ....No thanks. I would rather let them choose what they want. (Zucker, Tanev, Aston-Reese,...)

1st, losing Zucker isn't helping the team.
2nd they probably don't choose ZAR over Blueger or McCann of which you will lose one.
3nd if they were to take Blueger or ZAR, you will still be moving someone out for cap space. So you are going to lose 2 players. If you take Poulin out you are 3.8 million over the cap. If you remove POJ you are 4.6-4.7 and over the cap. Matheson is 4.8. You are over the cap. You'll be scrapping by on the cap and if you want to find a 3RD if Maniscalco or Friedman aren't it, you don't have the cap space too. You do realize that this is an issue. That most likely someone has to go. Which is why every other ACGM on here has them moving a defenseman. Simply moving ZAR, doesn't solve that. They will in the end have to move Matheson anyway. While I agree it shouldn't cost this much, the reality is, they can select ZAR anyway, leaving us with a headache. So just let them take them both and a 2nd and be done with it.

4th you need to create space in the lineup somewhere. They are so deep at LW. Jake, Zucker, McCann, Poulin. that's 4 guys who are probably close to if not already top 6 guys. By mid season he's probably playing for the penguins. You add in Caulfield by mid season as your bottom 4C, and you take Zoho as being permanent on the 4th line and what roster space do you have for him? Someone has to go if he's to play. It most likely means he goes to 3rd line and Tanev comes down to the 4th line with one of either Angello or Zoho coming out.
At this rate ZAR would most certainly be the one sat if he was on the team. Some one will get moved or sat if Poulin plays. There is no doubt about that.

You are going to have to make space on this roster. Competition drives a better roster. You can't keep everyone and you can't play everyone and you surely can't PAY everyone.
Even if you were to keep ZAR, where are you going to play him here. Yes you could play him 4th line. But for how long. You got bigger players who can play the same defensive checking role as he can. Who are all nipping at the heels. Where are you going to put him? Who has to sit for you to do that?
You just don't have the roster space to play everyone. Eventually someone is going to be the odd man out.
So they have to make it work somehow.
This is probably the easiest way to do this.

No, Pitts don't need Zucker at all, he is just too costly and handcuffs Hextall's hands...and for what? McCann will be playing at that spot or will be looking for someone new (maybe they fill it internally with Poulin).
I wouldn't mind to give up on ZAR, but I'm not willing to pay 2nd round. I would protect Crosby,Malkin,Guentzel,Rust,McCann,Kapannen,Blueger,Letang,Dumoulin,Pettersson. So they will be forced to take one of the names I mentioned earlier. If they take Zucker we have cap space, if they don't, we have other possibilities how to clear cap space. Trade out Pettersson for a pick. I don't get it why you think they're going to keep Pettersson over Matheson. I have faith in Friedman that he's the answer to 3RD, and if he isn't, it is not a big deal.

Because Matheson is far worse in his own zone than Pettersson and everyone knows this.
You already have POJ who needs to be sheltered in that 3rd role, you aren't going to shelter the whole defense and think that's going to help you win. Don't bother arguing that POJ point either he got benched this year when they had 0 defense healthy and his play at WBS hasn't been all that great since.
Giving up Zucker does not make the penguins a better team. He has far more value in a trade than ZAR and a 2nd. Moving Matheson to another team n a flat cap world probably isn't nearly as easy as you think.
This is the smart move. It would take more than ZAR to move Matheson to Seattle. If all they wanted was ZAR they could just take him. This way they get ZAR and a pick to take Matheson.
If you don't want Zucker there that's fine, you are more likely to trade him out for another top 6 winger than anyone else you are talking about.