Bison (nearly any cut) does not take well to high temps. The muscle fibers will seize and then you're done. Low/slow is the name of the game here. If there is little exterior fat and little evidence of good marbling (as is often the case) you might want to foil when the internal hits the low-to-mid 140s. Abandon any thoughts of comparisons to beef in terms of internal temps. Bison will often be tender at lower internals than beef, frequently much lower. It is, like beef and other Q meats, a question of time, not internal temps. Test with a probe for tenderness. If running an internal probe, start checking for tender in the upper 150s to low 160s, then every 20-25 min thereafter.
Bison brisket is delicious but many overcook it because they do not start checking early enough, or they go by beef temps and never test it at all.