Actually, I would argue the opposite. When revealed effects are completed prior to the Goblin being placed into the staging area and thus the spikes would not be attached to the goblin a it engages the player.
I think this is correct. My understanding is that the ordering is roughly as follows.
Take card from encounter deck and look at it. The card is now in-play but not in any particular zone such as the staging area.
Resolve Thalin-like passives caused by its being revealed.
Resolve the card's When Revealed effect.
Resolve any Forced effects triggered by its being revealed.
Trigger any Responses triggered by its being revealed.
Add the card to the staging area if it hasn't been placed anywhere else.
Trigger Ranger Spikes-like passives triggered by its being added to the staging area.
Trigger any Forced effects triggered by its being added to the staging are.
Trigger any Responses triggered by its being added to the staging area.
However, this isn't entirely clear from the rules, so I could be wrong.
Some other effects interrupt this sequence, such as Test of Will. I suspect the game would be more understandable if there were two types of "instant" abilities (e.g. Response and Interrupt) rather than just Response.