If you talked normally, it would've been nice, but you've been disrespectful using terms like "gtfo", while I haven't. When defending a cause, you should want that more people join that cause, and you would more likely convince more people if you don't insult them directly when they said something that bothered you.

Now about plants, it may be more complicated than what you just said. It's way more subject to debate. Even some vegan activists aren't sure about it.

And recently it seems a study showed that they may feel pain, but in another way:
"The team scientists believe that listening to different types of sounds that are emitted by plants could help with precision agriculture, and it can allow farmers to identify any potential issue with their crops. [...]
Last year, another study found that some plants registered pain after their leaves were touched and plucked, which eventually caused the release of foul-tasting chemicals across the leaves. It is believed that the chemical is released to ward off insects. "
Source: a study from Tel Aviv scientists https://www.sciencetimes.com/articles/24473/20191218/a-group-of-scientists-suggest-that-plants-feel-pain.htm