Since instructions are sequential, isn't this trivially true (barring something like Leyline of the Void)?

I think so. This is basically always Sorin, Lord of Innistrad's ultimate in miniature.

Even if it didn't, the morbid is also, um, in the way. Shouldn't the Morbid say "you may", so that it didn't become a drawback in some situations? I wouldn't be so fond of having this when my opponent had a Nantuko Shade on the table, for example.
"Death Conversion your Black Titan?"
"Sacrifice a Zombie Token in response?"

You can only return the targeted creature, so you don't have to worry about your opponent tricking you into a different creature. I made it optional anyway, in case you run into a Phyrexian Dreadnought or something.

Dreadnought isn't much of a bother because it comes back and you just sacrifice it again and no harm done.

There's still the larger issue that this is just Ritual of the Machine without the sacrifice cost and with a broader targeting condition.

Hmm. So it's Mind Control that doesn't work on regenerating creatures. Odd.