Have to think the last component there, "they're apart on usage" is a big element in this. With Byfuglien and Myers already there on the RH side and making money, taking up PP time, etc., it's not hard to see how Trouba and his agent might be looking at the situation in Winnipeg and come away a bit skeptical of the opportunity for him to really take on the role he wants and is entirely capable of.
He's gonna have a hard time earning the huge payday he's capable of earning, if he's stuck sharing those RH defenceman opportunities with Byfuglien and Myers for the next bunch of years. At best, he ends up playing on his off side at even strength, which is very unusual and likely not very desirable at all for a RH shooter...and he's still splitting PP time.
Other teams, he's probably playing top RH defence minutes, top-PP time...and earning a future contract accordingly. I'm sure Trouba and his agent can see that.