The Feänorians 'kidnapping sailors from Alqualondë', as you name it, is a personal headcanon of mine. The workings of a ship are intricate, and you do need someone skilled to sail it, especially with the storms Ossë was making at the time. I doubt there were enough Noldor who could sail that many ships through Ossë's storms without some ending up on the sea-bottom, and just letting them dumb Teleri sail them would just be practicality. 

As for those lines, Tîrpethron and his family have been receiving strange stares for four-hundred and seventy-two years at the least, because they did nothing when the Fëanorians took their ships at Alqualondë but still grieves over their lost ships. Nobody understood them, not the Sindar of Nevrast ("Why would you just go with them? You could've fought back!), nor the Noldor of Gondolin (They are just ships, what would it bother you?"). He speaks to Círdan about it because he knows Círdan will understand what a ship means to a sailor, and that you'd rather go under with it than see it in the wrong hands. Círdan nods in acknowledgement of the story, and grimly because, well, Alqualondë. That'd make any elf grim.

Thanks for the comment!

Thanks for the comment!

It is said in the Silmarillion, chapter 12, Of the sun and moon and the hiding of Valinor, of the Enchanted Isles that "Hardly might any vessel pass between them" and "and of the many messengers that in after days sailed into the West, none came ever to Valinor - save one only: the mightiest mariner of song."

But Valinor is defined as the region beyond the Pelóri, and it does not include Tol Eressëa or Alqualondë. Plothole found! They could stay there, if their vessel could pass between the Isles. And so, in my special place of fanon, I grant these valiant mariners mercy (after all, this is fanfiction).