That's where the saying "You can't chain to a summon" takes place. Since declaring a summon has no Spell Speed to chain to, you cannot activate anything until the monster actually touches the field. (which is why you can't use Waboku at the last second just so a Jinzo about to be summoned can't negate it).

Horn of Heaven, Solemn Judgment, Royal Oppression, Forced Back, or any card that negates the very summoning of a monster(s) PREVENTS any sort of priority from being declared since it's almost like (not literally) the summoned monster never hit the field to begin with. And since there was "no monster summoned", then there is no priority to be declared.

Ah, ok, I see what you're saying. Even though Exiled is already summoned and the opponent uses his priority to activate his effect and tribute it, because the cards negate the summon, they are pretending as if they were chained to the declaration of the summon itself, although because of the zero spell speed, that isn't what actually happens... Thanks, that just cleared up another little cluster of questions and doubts.

Yeah, pretty much...except they are never able to declare priority and activate Exiled Force.

Basically, it's almost (not entirely) like how it's done in the GBA game, Yu-Gi-Oh! Ultimate Masters World Championship 2006. As soon as the monster touches down on the field (assuming there's nothing else going on), you get asked if you want to activate Horn of Heaven, Solemn Judgment, etc and can use a summon negating card to negate it before priority can be declared.

That's the closest I can think of describing it.

Take this small ruling under Forced Back, only if it means something or helps in anyway:

You can activate "Forced Back" when you Normal or Flip Summon your own monster. You should announce this immediately after your Summon. Once you allow your opponent to activate "Torrential Tribute" you are acknowledging that the Summon was successful and you cannot activate "Forced Back".

Yep..pretty much like with a lot of other cards...you can't suddenly decide to "take back" things when you see you made a mistake in doing so, lol