Resistance negation works, like all other haxes, up to where indicated in the array. If it is not shown to work on BFR, it is not assumed to work by default.
Ultimate Skill users have resistance to resistance negation which only works on sleep manipulation so it doesn't mean anything.
While Rimuru cannot even analyze Veldanava, Ciel will prevent Rimuru from approaching Veldanava. That's why Dragon Spirit Haki doesn't have much use here.
Also, why are we talking about Immo Type 5 when Rimuru won't even try to kill Veldanava? WN Rimuru can't analyze Veldanava, so Rimuru will be very careful with Veldanava, just like he was with Velda, an enemy he knows nothing about in the WN story.
Finally, since the OP didn't specify, I have to ask, is the speed equal? (I already assume we are at SBA)
Even in the Psedue True Dragon key, Rimuru resists Chloe's Ultimate Skill that control Veldanava's system and he can also resist Shion's Tyrannous Lord Susanoo, who has complete control over the laws of causality in the EoS Key.