Here's how I see it.

Minimum Bid Period Guarantee - 4a1 sets this at 68/85. Normally Bid Line Guarantees are built above these values. When the company built below these values, they bought up to these numbers.

4a2b - The minimum bid period guarantee shall be reduced to a minimum of 48/60 CH before any pilot is furloughed. At least a full bid period must follow the announcement of this action. This provision shall only be used to prevent or delay a furlough.

Ok, 48/60 is the new MBPG. They can build above these values, but if built below they must be bought up to these numbers. Never implied that the company could have them above 68/85. But as we all know, there is no language in the contract that is keeping them from doing it now.