Soliola's defence lawyer Nick Ghabar argued that the hit on Slater was careless and not reckless, and that the Raider deserved only a three-week ban given the Storm fullback was falling in the tackle.
But in a 100-minute hearing, NRL counsel Anthony Lo Surdo told the three-man panel that the hit was reckless and needed a six-week ban.
Soliola, a former Kiwi international, will be able to return for the Raiders' round-26 clash with Melbourne.
Ghabar also argued it "would've been very hard" to pull out of the tackle.
