Griffin and his team have plans and projections for the future, but it's a pretty complex thing and I don't know that we can expect him to have it all mapped out and planned for.
The team had some serious deficiencies and Griffin had to make trades happen to correct the deficiencies. He was therefore stuck between a rock and hard place because he probably realized that these role players he traded for would eventually want bigger money, but if he didn't make the deals then how could the Cavs compete for a title? My guess is that Gilbert just told him to get the players in and they would try and figure out how to make the payroll work later.
I also doubt that Griffin was projecting Tristan as a max contract player. Tristan turned down the 13 mil per season, but I doubt Griffin expected him to demand a max deal a year later.
So now the Cavs have a team that is good enough to win a championship, but they may need to drop a player or two in the next couple of years to make it feasible financially. It happens pretty often. Splitter was a luxury the Spurs couldn't afford. David Lee was a luxury the Warriors couldn't afford. Based on TT's connections and this perfect storm of events, it does not appear that TT is going to be the guy who gets kicked to the curb.
Assuming Tristan gets locked up long term, these are the players who would seem to be on the hot seat:
1)Mozgov
2)Andy
3)Jr
4)Delly (unless he willing to continue to play for right around the minimum)
What the Cavs value Tristan at is almost irrelevant at this point. The Cavs are more or less obliged to pay him because they can't risk losing him for nothing and they are probably unwilling to risk the fallout from LeBron if they don't keep Tristan. So, under duress, they value Tristan quite high, but in a vacuum I doubt they see him as worth much more than the 13 mil per year they offered him a year ago.