Some thoughts after reading that.
So it seems as if we don't know. Bhai Daya Singh's response was quite strange, he says that was Goddess present there. This is more akin to some RSS propaganda I have read. It's hard for me to differentiate, and it only confirms what the RSS say.
And would Bhai Daya Singh's rehatnama be more valuable than others since he was one of the five?
The whole article suggests that it's not clear which banis were read. So if we don't know which banis were recited, why have a set of banis under the nitnem heading? (especially when most of them are not from SGGS, which is a whole topic on its own)
Why enforce this "law" without any basis or until things are cleared up?
And I am bit confused by his humble inquiry