I think but could be wrong, it was cheaper to pay him his salary in 2024 than take the cap charge if they had released him. Its the only way I could explain this.
Per Spotrac.com, when he signed with the Birds in 2023, it was a 3-yeard, $38M contract. It included a $7,985,000 signing bonus. The kicker was that the signing bonus, the 2023 salary ($1,165,000), the 2024 salary ($1,210,000), and the 2024 option bonus (I think it was $1,528,000, but I'm not certain of that) were guaranteed. So cutting him last year did not make much sense from a dollars perspective. He would have been a $4,305,000 cap hit in 2024, and a $15,118,000 dead cap hit in 2024.
His being on IR helped both parties.