Briere needs cap room in 2024-25, has only $3.8M, and has to sign Fedotov, and Johnson or rookie will eat another $1M, but $39M in 2025-26.
So buying out Peterson, Atkinson and Johansen saves $10M in 2024-25 and costs $5M the next season.
Even if Johansen was injured, unless it's career ending (in which case he's a LTIR candidate for one season) he'll be bought out as soon as he clears his medicals.
They have Ellis' $6.25M for the next three seasons, which they can put on LTIR (in summer, can go 10% above cap so it's not needed) but would prefer not to since you can't accumulate cap room during the season if you do so.