Afaik the “Magnesium white” colourway on Offset’s throws is the same finish as Moonrock and I and quite a few others have had issues with this finish (which for some people was worse than just string cutting): Moon Rock Bearing Post Issue?
Brandon’s been very good at making the string cutting issue clear, unlike some other brands unfortunately, and masking the hub should help a lot with string cutting.
That said, I would still just avoid the colourway and choose one of the other options personally. Better safe than sorry.
Also, I’m sure you know but just so it’s clear, the white colourway isn’t actually a magnesium yo-yo. That’s just the colourway name.