The law in question came around for a good reason:
Section 75 came about as a result of a sweeping review of pension regulation in the wake of the Robert Maxwell scandal in the 1990s.
Following the media tycoon's death it emerged he had plundered millions from the Mirror Group pension scheme.
The Pensions Act 1995 introduced a series of reforms including a "minimum funding requirement" for pension funds. It also introduced something called "Section 75 pension debt", which meant if an employer "departed" a scheme, they could still be pursued for any shortfall.
It is just a poor match with this type of shared pension scheme (not British, so forgive problems matching this to other types of defined benefits plans I'm more familiar with). This seems to be a clear case to revise this Section 75 for these types of group plans/schemes.
There is no actual fiscal problem here, just a legal one. The biggest obstacle to amending the existing law, based on the article, is an inability to enact legislation because of distraction by Brexit.