I had an interesting series of cascading effects occur during a game against Eihort tonight. It was late in the game, and there were 8 tokens on the doom track. I was playing AH and IH, with all investigators, cards, etc. except only the gate and mythos encounters from the two big boxes.

Tommy Muldoon had a couple of brood tokens, sealed a gate and got devoured. I placed all his brood tokens on Eihort, then removed one, leaving me with 2 spots left on the doom track (10 of 12).

The new investigator was marie Lambeau, replacing Tommy. Her personal story says that if the doom track is at 5, she fails. I played that this was an immediate fail. Boogers! Her fail effect was that the terror level immediately increases by 1. Complicating matters was the urban environment "Happy Days are Here Again" which states that the terror level can't increase. I played it that the terror level didn't increase,plus, I had Tommy's lingering effect that the terror level I get a pass one time on the terror level. I left that in play, ruling that the terror level couldn't increase because of the environment, so Tommy's pass effect remained for later use.

As it happened, Tony and Mark (replecement for a previously devoured Silas when he passed his personal story) sealed the final two open gates and I won with all gates closed.

I think my logic was sound, but wanted to get the opinion of my esteemed colleagues on the forum. Did I do this correctly?

That sounds right, yes. Interesting Tommy/Eihort idea... what would happen if being devoured put Eihort up to the end of the track: would Tommy remove the doom token before or after they woke up? (I suppose, as usual, first player decides)