No, and AFAIK Shalit never converted to Islam either.
How about his father, mother and commander-in-chief? [chuckle]
Haqqani commander is quoted as saying Bergdahl DID NOT convert to Islam.
Also the “military source” that initially reported the conversion, also reported at the same time that it was part of Bergdahl’s plan to gain an opportunity to escape. He gained his guards trust until he was rewarded with enough freedom to slip away from them. He was captured three days later.