problem arises because people with next to nill understanding of Dasam Granth's style attempt to make scholastic comments on it.
Guru maharaj uses sooooo many names to refer to Akaal, that the unwise, or the weasel find all sorts of so called "discrepancies" with Gurmat.
If you have doubts that Guru Gobind Singh directed Sikhs to worship Akaal only, then you know absolutely nothing about Guru Gobind Singh ji's character.
All devis, rakhasa's, devs, munis....all originate from Akaal. Guru ji will use any name he wishes to praise Akaal....and there's nothing idiotic blokes can do about it.
How, or why, would Guru Gobind Singh, having the same Jot of Guru Nanak, which is Sargun Nirankaar ( God manifested) pray to his own created sevak (Shiva) for strength!!!!
So for any those RSS types lurking on this forum ( yes, they are here!), Guru Gobind SIngh is referring to Akaal as shiva in "deh shiva".