no, your bankai is always more powerful than your true relses and since ruriiru kujaku is an insta kill its safe to say that his bankai is off the charts....
and kenny doesnt trat his zanpakuto with absolutely no respect so he would lose no mater wat
except Kenny does not lose... ever
he tied once but has not lost
Ruriiru is not an Insta kill, insta kill would not leave room for 9 to 10 pages of discssion after using it it
Suzumebach is far closer to being an insta kill
he beat a lowly Fracción with an attack and all you can see is it being uber great
I can see lots of different people that could beat it
Tessi, Azian, Byakuya, and probly Hachi as well could use Danku tha barrier that blocks Kido
as a Kido based Zanpukto it would most lickly be suseptable
Yoruchi, as this is a Kido ability Yourchi could use Hanki to stop if from working
Hanki is what she used on Soi fon to stop her Shuko
it nullifies Kido by hitting it with opposite energy
Ishida or any quincy for that matter
Rurriiru drains a person SP but quincy do not fight be using there SP they use absorb the SP from the area around them
Yumichika is a one trick pony sure he has good combat skills but only one real ace up his sleave
and once that is out of the way he is done