What is your evidence for that?
It's a critical ferry port on the West coast with numbers far higher than the Jacobite. Plus the ScotRail services, plus those who visit as part of the road to the Isles, and those who stay locally as there are a lot of local b and bs.
What is your data to back the claim about a majority?
I only have my experience as a Jacobite customer, but it seems intuitively obvious that when you have several hundred passengers arrive twice a day, and who have a couple of hours to kill, most of whom will also be hungry, with not much else to do, the shops and restaurants are going to benefit hugely.
In contrast, ferry traffic will tend to be just passing through. In one direction they will typically just drive off and get on with their journey, and in the other will arrive in good time, but not hours in advance.
Is it a majority of the tourist spend? I don’t know, but it’s clear that it would have had a huge impact on a small town that would have been expecting several thousand visitors a week to spend their tourist pounds there and geared up (eg staffing) accordingly.