I dont claim to be historian, nor well-researched on the topic. So it's just based on my logical conclusion.
Especially on "what were the rules at the time?". So how do Jujutsu and Judo duel in 1888 if they have different rules? So both must have unified rules. So old Judo at the time was just "sport jujutsu" instead of "street jujutsu". With the emergence of Fusen-ryu, Mataemon Tanabe
DNBK does have influence from Jujutsu (they have Jujutsu committee as previously mentioned), and they set rules for Kosen Judo (even though they are team 20v20 like Quintet).
With the history of
But from big picture point of view, they are adopting mainstream Judo at that time, which is Kodokan style. Which at the time it was ippon / pull guard newaza rules (else, how do 2 side agree to duel during Tokyo Police tournament?).