We're already in the middle of a rebuild. We still needed reliable vets hence signing the old vets.
Through absolutely NO FAULT of your own(Poile is to blame), and identical to my favorite team's fanbase, you have never known what a rebuild is, but it's that thing the Sharks, Hawks, Jackets, Ducks are doing which you probably call "tanking". It is not making the playoffs a 9th time out of 10 and signing two 40 goal scorers to further strengthen the team. Reminds me of when my team signed Gionta and Cammalleri and traded for Gomez instead of rebuilding. Our fanbase stands strong with yours as we've both watched all these amazing teams draft these even more amazing players like McDavid, Hedman, MacKinnon, Barkov, Kane, Crosby, Ovechkin and Doughty, develop them, build teams around them and win cups while we were debating which bust we wanted with our 15th overall pick.
You should absolutely NOT want to trade a 1st for Matheson, bad fit anyway because Josi already does his job, but you are not in the middle of a rebuild. You guys have luckily had a fantastic start so far though. I hope for you that you can finally draft a forward better than David Legwand or Filip Forsberg, like every other team other than yours and ours gets to have.