Why Does the Bivector Higgs Field Define Custodial Symmetry in Equations 45-51?

[ChrisVer]

http://arxiv.org/pdf/hep-ph/0410370v2.pdf
Can someone help me understand why in the Sec. 3 Custodial Symmetry, Eq 45-51 he goes all the way in defining a bivector Higgs field in the way he did?

 

[RGevo]

Check the first few slides here
https://indico.cern.ch/event/117033/contribution/10/attachments/55749/80218/Dudas_L4.pdf