I know what a true combo is, and my use of the word "seems" in that post was very deliberate, as I tested it only briefly. You're correct to say that "combo" is a more fitting word for it.
As for JC throws being less laggy than dashing throws, I'd say you're correct on that, as well. Though saying they're "much" less laggy is a bit of an exaggeration. Link's running item throw animation recovers extremely quickly in this iteration of Smash compared to previous ones. Is it faster than JC throwing? I don't think so, but the frame difference between them is very small. The other thing is that JC throwing halts all of Link's forward momentum, whereas the running bomb throw animation has Link continuing to move forward a couple steps even as he tosses the bomb. For combos, grounded rushdown, and gap-closing, I'd say the running bomb throw is almost indisputably better.
I agree with you that JC throwing is the better tech overall, just so you know. The running bomb throw is only useful for offensive play, whereas the JC throw accommodates both offensive and defensive play.