According to Listing Rule 3A, a sponsor cannot have a current business relationship with the new applicant, which "would be reasonably considered to affect the sponsor's independence in performing its duties, or might reasonably give rise to a perception that the sponsor's independence would be so affected".

I suppose that several hundred million dollars in fees (on a $5-7bn offering) isn't enough to affect the good judgement of the sponsors. Haven't we already learned how craven Morgan Stanley can be even when it's not affiliated with a company?

The major concern is that this "issue" might delay the offering:

In order to resolve the issue, it may be necessary for the Hong Kong Exchanges and Clearing's listing committee to hold a special policy meeting in order to seek opinions from all members. If members do not agree to a special meeting CCB's planned US$5 billion to US$7 billion initial public offering, due to kick off next month, seems likely to be delayed as the next scheduled policy meeting is also in October.

The SCMP floats the idea that this problem could be solved by adding CSFB to the list of underwriters, despite the fact that Credit Suisse is still negotiating a $500m investment in CCB. Pardon us if we can't see the added independence here.