Vegetarians who say this shit say they enjoy getting encouragement from vegans, but they actually just want a pat on the back and brownie points from susceptible vegans, not actual encouragement.
This is the greatest encouragement I can give them, but because it's in an "aggressive" tone, they love to say "You're the reason why people shy away from going vegan!"
Sorry to tell ya, but if some harsh words promoting the very ideological foundation of veganism are enough to discourage you, then you clearly don't have a plan to "transition" to veganism to begin with.
Imagine telling someone "You really need to stop being fucking racist." and then they say "Ugh! I'm working on it! You being so pushy makes me want to be more racist actually!"
The cheese rots into their brains apparently.
The practical stance is that you need to educate non-vegans with a sense of urgency to be adequately encouraging. You need to emphasize the importance of cutting out animal products. The notion of "transitioning to veganism" is flawed, yes, you get it. If you can acknowledge that, you can acknowledge that if you're interacting with a cheesebreather who says they are "transitioning", they view the matter of animal liberation on an entirely different premise than you do.
Call it "hostility" and what will "push people away", but these cheesbreathers need to hear views that encourage them to be immediate when it comes to going vegan. Hell, even if you phrase it in a "non-hostile" manner, these people don't like anything but a pat on the back.
It doesn't matter if you say "I think it's great that you're trying to transition, but I'd encourage you to do it as immediately as you can. Dairy and eggs are still very harmful, and you're not making much of a practical difference by merely cutting out meat." or if you say "Vegetarianism is bullshit. Cut out the byproducts right fucking NOW!". The truth of the matter is that they don't want any pushback whatsoever, no matter how "nice" you may be about it.