Muni techniques???

I was browsing some muni tips and came across this site
most of the tips seemed helpfull but i was wondering about no3- which says

{Now if your not holding the seat with one hand, shame on you! Hold on to it by pulling up underneath it as hard as you can so that you can deliver way more force to that forward pedal. The extra force generated by pulling up on the seat will let you climb hills over twice as steep providing you can stay balanced on the way up with only one balance trim arm. }

Is this true… i always thought an extra arm waving around was helpfull?
Any ideas would be appreciated!!

For most slopes, that extra force is not that helpful. For most slopes, the key thing is feet working together over the entire cycle.

However, what the seat-holding does is stabilize the saddle-body interface and allow quick stabilizing hops.

The second balance arm is not necessary, though it may take a little while for this to be true for an individual rider.

For steeper slopes, then the pull on the saddle for extra force on the pedals is important.