"Alternating" doesn't make much sense. It's not as though they have a history of going back and forth and back and forth. Every studio album through FWX was on Metal Blade. They then did DIADL and TOF on Inside Out, and now they're back to Metal Blade. Maybe if, after releasing a couple albums on Metal Blade, they go back to Inside Out, you can call it "alternating," but the foray with IO seems otherwise to have been merely a brief diversion.
Not sure why it is hard to accept. I didn't make it up.
They have said, more than once, that they have great relationships with both Metal Blade and Inside Out, and are alternating deals. I don't have links, but they've said it repeatedly. Both Jim and Ray's last solo records were on Inside Out, whereas Arch/Matheos was on Metal Blade. Maybe they meant that between both labels, all their music will be released? I have no idea, you'd have to ask them.
I don't know the reasoning behind it, all I'm saying is what I heard in interviews over the last several years. Maybe I misheard? I don't think I did, but my old fogey status makes it a possibility.