The quote referred to...
That was when Joshua led the Children of Israel into the Promised Land and displaced the people currently living there.
Unless you are saying that the reason God supported the Children of Isreal was because they were illegal aliens then your analogy is as hollow as a pinata. One must also assume that God always supports illegal aliens and that the story of Joshua was kept as Scripture in order to demonstrate that.
If you feel you must derive the rule that God "always" supports illegal aliens, then go for it.
I see alternatives.
However, in that particular instance God did support them.
"Since God did X in situation Y, then God will always do X for any situation" does not seem to be logical to me.
That does not change, though, that God did do X in situation Y.