I mean, an entire religion was formed around insights around suffering, so clearly people have been thinking about this for a long time!
It's not comparable, they're two entirely different forms of life, suffice to say, they both suffer, discussions around how people can directly if not reduce suffering mitigate it.
Telling people to only eat vegetables because suffering animals or it's cool eat meat because suffering plants is an utterly pointless topic of debate.
A more useful topic for debate if we're going to talk about such things would be maybe something like mitigating the suffering on both plants and animals through industrialized agriculture by returning to small scale production of both. Or something like that anyway.
The article as framed just didn't really talk in any useful way about the issue.
Which, if you are serious about ending suffering, a plant or animal grown in a small scale way where it can be looked after properly is going to suffer significantly less, even if it inevitably will die to feed somebody.
Personally, I'm a vegetarian because I find it unethical to eat animals for many reasons. Their individual suffering, the environment, my personal health. Of course even within that you have to be careful, because going vegetarian but only eating food flown in from around the world isn't too great either.