They would prefer a barbed single stuck in the fish or a body part  as opposed to a barbless treble which will come out easier of both concerned.....go figure.

My advise.....Dont buy those because they need trebs...........get a shimano ocea pencil or a starwalker (larger one /both floaters) and stick 7/0 inline shoguns on them with 9mm decoy splits......All  easily available where you are.

The treble on the belly helps with stability..........another factor is the combined weight.....esp when they are surface or sub surface lures and need to pop back up........

Personally i dont think the action of the orcas is that flash....even with trebles.....I am sure they could work with inlines but i bet their action will be reduced.....Go try and find out!.......I am speculating...so i cant say for sure.......put some time in and see for yourself.......buy one and try it out and then please let us all know......I have a few with trebles.

The two i mentioned work well with inline 7/0 because i have used them like that for ages and trialed them like that but you go to a tackle shop and they will suggest 3/0 trebles for the ocea pencil.......originally the starwalker came recommended this way but i found both were slow to pop its head back up for the next stroke as well as less action......so too heavy.......the 7/0 inlines reduced the weight.....livened up their action and their head popped up quicker ready for the next stroke........The River to sea "rover" is typically fished with two trebles(this is a total surface lure) ...have found it goes well with treble belly and nice size inline off the back.

             There is no doubt......some lures were designed for trebles and dont like to be messed with via single hooks.........Then you have lures like sams(on here) Reel Appeal Lures (RAL) who makes his lures specifically for inline singles...Nothing is set in stone and there is nothing wrong with trying stuff out....Give it a go.....Good luck