My understanding of the situation is that the ferry administration (Washington State Ferry) is being unhelpful. I can see both sides of the selling CD issue, though claiming Security is BS. There is a galley which sometimes is open, and those workers do not have to leave the ferry at each end, carrying their belongings. They have gone through a process to be screened, and are allowed to sell food/drink and stay on board. There is no provision for David to do this, beyond (from article in OP)
if Michael wanted to play onboard a ferry - and not have to carry his harp off and on the boat - he could pay a fee of $200 per boat, per day (the going rate for the PT-Keystone route). According to the promotional activities policy, he would be restricted to a certain area of the boat and could not go around soliciting passengers. He would not be permitted to sell CDs or "engage in retail activity."
As another option, Michael is welcome to play for free, not sell CDs, and take his harp on and off the ferry at each stop.
When this came about, he tried checking with the WSF to find out about their table top promotion rules (getting a pass, paying a fee, selling on ferries). They put him off while researching and changing ferry guidelines to reflect busking vs table top promotions. My understanding is that some astute person checked the guidelines pre and post contact and found they changed the guidelines. oops.
He is working with others, trying other options since he loves music, loves busking, and needs to sell to survive. Someone wondered if the consession that has the galley might hire him as an employee for a minimal amount, sell his CD's, and reap the harvest of those who travel the ferry to hear David play (and yes, he does tell people that there is a galley, to go get coffee and food).
Someone else is working on buskers rights on the ferries, organizing a Busk In on one of the Seattle ferries sometime this fall. If I hear about it, I'll post on DU. This would be not just about David Michael and his Dangerous Harp, but about busking in general.
Finally, the publicity he has gotten from this incident may have good things happening as far as his music. Nothing for sure, but perhaps a good thing happening. However, he still loves to play in public, it is what he does.
So, I'll post more if I hear it. They say at this point contacting WSF won't do much good, but thank you for all the support.