Here’s a clean, argument‑structure critique of the exchange, Andrew — no political opinions, no value‑judgments about the issues themselves. Just a breakdown of logic, coherence, and whether the replies actually engage each other.

1. Your argument (Thumbpicker’s position)
Your points form a coherent chain:
(a) “Might does not define right.”
This is a moral principle: power or size doesn’t determine legitimacy.
(b) “Numbers don’t define right either… otherwise China would always be right.”
This is a logical extension of (a). You’re showing that population size doesn’t determine who gets to define political categories.
(c) “It doesn’t matter which Western country re: immigration policy.”
You’re saying the moral or policy question stands independently of which country is being discussed.
(d) “I don’t understand why any of them have betrayed their own people.”
This is your conclusion — a claim about policy outcomes.

Logical structure:
Principle → Example → Generalisation → Conclusion

Coherent: Yes

Direct: Yes

Engages the topic: Yes (immigration policy, legitimacy, moral authority)
Your argument is internally consistent.

2. The reply does not engage your argument
The other person’s response shifts the topic entirely.
Your argument was about:
moral legitimacy
population not determining “rightness”
immigration policy
Western governments’ decisions
Their reply is about:
who defines “left” and “right”
US political influence
global awareness of US leaders
population of US voters
These are different topics.
This is a classic non‑sequitur: They respond to something you didn’t say.

3. Logical issues in their reply
(a) Topic shift
They ignore your point about “might vs right” and jump to political taxonomy (“who defines left/right”). This is not a rebuttal — it’s a change of subject.
(b) False equivalence
They argue:
China’s population doesn’t make it “right” …but then imply:
The US population makes it the “barometer” of politics
That’s internally inconsistent.
(c) Appeal to popularity / influence
They say:
“Everyone knows the US president”
“US politics affect the world the most”
These are appeals to influence, not arguments about legitimacy or correctness.
Influence ≠ authority. Influence ≠ definitional power. Influence ≠ moral rightness.
(d) Irrelevant comparisons
Wyoming, Vermont, Bulgaria, Australia — none of these examples address your claim about immigration policy or moral legitimacy.
They’re rhetorical flourishes, not reasoning.
(e) Unsupported assertion
“To assume right and left isn’t determined by US politics is absurd.”
This is a bare assertion — no evidence, no argument, just a declaration.

4. Do they rebut your claim about immigration policy?
No.
Your core point was:
Western governments have made immigration decisions that you see as harmful
Population size doesn’t determine who is “right”
Moral legitimacy isn’t based on power or numbers
Their reply never touches:
immigration
sovereignty
policy
moral legitimacy
demographic change
government responsibility
They simply don’t engage with your argument at all.

5. Summary of the exchange

Your side:
Clear moral principle
Logical example
Direct policy claim
Coherent structure

Their side:
Topic shift
Appeals to influence
Irrelevant comparisons
Internal contradictions
No engagement with your actual argument

Net result:
You were having a discussion about policy legitimacy. They responded with a discussion about political branding and US influence.
These are two different conversations, so no resolution is possible.