No, it isn’t. Lydman is a Swedish name and while the vowel is long, it doesn’t sound anything like “O”. According to this guide, Swedish “y” is “similar to the French u and German ü”.

I don’t speak any French or German, so I have no idea how accurate that piece of advice is, but there’s also an audio clip of the Swedish word “dyr” (expensive) which has similar long “y” as Lydman.

(The NHL pronounciation guides are often quite funny from a Finnish point of view. “Niemi” is certainly not pronounced nee-YEH-mee, for example.)