Well, you could think about this this way
Both have 4 years left on their deals. Tkachuk at 8.2 and Chabot at 8.0 (iirc off the top of my head)
If we trade Tkachuk, we're getting a massive haul in return
If we trade Chabot, notwithstanding his recent stellar play, we're probably stapling assets to Chatbot to be rid of the contract
One player is a bargain and the other is a bit of a cap dump.
Personally I'd take the contract bargain
Let's take a step back, Tkachuk isn't a bargain, he's living up to his contract and playing its worth. Chabot isn't going to require us to pay to move, he's not Darnell Nurse. What each player gets in a trade haul is irrelevant to how Chabot is a more rounded player than Tkachuk is, and that doesn't mean Tkachuk is less valuable or Chabot is more valuable.
Judging each players value to the team based on what they'd receive in a trade haul ignores the context of how the players have gotten to where they are. Chabot has had to carry the blue line while playing 25+ minutes for several years and its broken him to the point where he appeared to be too indecisive to be our top D. We gave him an above average RD to play with, and he's now an invaluable piece of the team.
Tkachuk is a power forward unicorn who shoots and hits like crazy. That's super valuable, and after having played with the best players we've had, he's developed into an amazing offensive threat. His defensive game hasn't caught up and we need it to for us to be successful.
We need both players to be successful, but it's easier for Chabot to get going because he finally has the bare minimum for a defensive partner, and now he's effective on both ends of the ice. Tkachuk's growth in his own end depends entirely on itself.
So Chabot has always been a 2 way defender? His goal high is 15 and has had over 41 pts once. He's always been a negative player every season in the league.
He's playing well this year after a couple of poor seasons but the excuses made for him boggle the mind.
Context matters mate. He's produced at a .59ppg (49 point pace) his whole career, played 24+ minutes for every season until Sanderson's emergence, and done it without adequate D partners. Also the list of players in our core that have an overall postive +/- after the last 6 years is very small and doesn't mean much when evaluating their defensive ability.
Chabot is by every definition a two way defender, and a more rounded player in his respective position than Tkachuk is in his position.