Seafoam does nothing to loosen spark plugs.
I know....I laughed out loud awhile back when I read that he runs some through his engine prior to plugs. But hey, if it makes him sleep better at night..?
To me, having clean "snouts" on plugs that I'm about to replace is an important thing. Maybe he'll make a youtube video about that too, to go along with his oil gauge install...LMAO
Putting a drop of antiseize on the threads will actually have a benefit to future removal, or maybe it won't. But I wouldn't waste my money betting on (or buying) seafoam with the goal of easier plug removal...because it won't help with that at all.
The seafoam burns in the combustion chamber as the engine is running. It's not going to penetrate the threads and give you any kind of noticeable result.
PB Blaster will, if you remove the coil and spray it down in the hole and let it sit for a bit. I use it on every bolt, plug, or fastener that's not in the interior on everything I work on. The only bolts or nuts I've had that wouldn't come off since I can remember are the front upper ball joints, and seeing as how they were fairly loose, I just cut them and replaced with greasable UCAs.
Honestly, plugs are a straightforward job (if you're not messing with two piece units, that is)....take em out, clean the holes, and replace. I think you're making more of it than it really is.
How much is seafoam, anyway? I haven't bought any in something like 20 years. Don't need it...