Setting a preference order for the purpose of Must-Haves and Unacceptables does not necessarily impose preference order on the final utility estimates in ACBC. It only guides the logic of how Unacceptables and Must-Have probing questions are asked.
When you impose preference order, the Must Have probe will ask the respondent such things as if they must have "at least 50 channels". But the respondent doesn't need to pick this option if he/she doesn't feel it is true for him/her.
Also, for the Unacceptables probe, "less than 50 channels" would be offered as a possibility to choose as a rule that expresses the respondent's preference. But, the respondent doesn't have to pick it.
So, individual-level respondents who feel that too many channels is actually a negative will be able to express themselves via their choice tasks (the BYO, the Screener section, and the ChoiceTournament).
During utility estimation, just make sure to NOT impose utility constraints on the estimation for this attribute.