Well, there wasn't any sponsor for the fire extinguisher holder or the herbicide table. The genetically modified plants (that can result in the sim-eating plant) and the organic recipes (that can result in a fire) were a change made to the game in the October 2012 Supernatural update made by EA Mobile (the developers of the game at the time) on their own so there wouldn't have been a contract like with Katy Perry, TOM Shoes, or Apple.
It's possible they were saying that with tongue in cheek - it was not a change to the game most players were happy with and with the next update or two there was a pop up that said something about 'due to a contract with the sim-eating plants...' and went on the explain how the fire extinguishers and herbicides would be removed from the game and there would be one flat negotiation action that we wouldn't have to pay simoleons or LP for.
It's also possible that they said they couldn't bring them back and instead of meaning they couldn't bring them back because of a contract with a sponsor they meant they couldn't bring them back because they couldn't or wouldn't be bringing how they worked back. Right now the fire extinguisher holder and herbicide table are non-interactive items and only people who had purchased fire extinguishers or herbicides in the grocery store during the Supernatural update would ever have fire extinguishers or herbicides appear in the fire extinguisher holder or on the herbicide table (but can't interact with them).
And it's also possible that the person responding to the question on the Facebook page just doesn't know what they are talking about. And I don't mean this in a mean way or anything. It's just typically the social media people aren't around for the long haul and aren't likely to know the history of the game and, if they are new, the right answers. I can always tell when they've got a new person responding to comments because they'll give some incorrect answers about things (town value being the reason building prices are increasing, ugh! no!). There could have been a misunderstanding when the social media person went to ask someone about the fire extinguishers and herbicide table.
The fire extinguisher did show up in an architect house once so I wouldn't rule out it or the herbicide table showing up again.