All it says in the instructions is -
AUTOMATIC CHARGER FOR 12V LEAD/ACID BATTERIES.
Recommended for charging batteries of from 2 to 30Ah capacity, and for maintenance charging of batteries
from 2 to 50Ah capacity. Do not use for NiCd, NiMH, Li-Ion or non-rechargable batteries.
It says nothing of gel batteries :dunno
Pick the bones out of that.
the gel batteries and pulse chargers are imho a HOAX. there is no pulse charging on the motorbike so any battery charger should be ok to charge gel batteries. otherwise it will not be suitable for use on a bike (or car)
the gel is just a mix of acid with a powder to prevent spilling and leaking.