Incorrect.  Someone who says "diversity is our weakness" may be absolutely fine with immigration but be expressing a view that accepting all diversity of traditional cultural expressions over what is acceptable in a modern, gender-egalitarian Canada is our weakness.  That by not expecting immigrants to drop certain diverse practices in favour of what's acceptable today in Canada is our weakness.  (Again, I'm not saying whether or not I agree.)  But because you are a liberal/progressive you jump to censor, will not allow the expression ("then you shouldn't use that phrase"), will not consider an exploration of the person's meaning, so you have no option but to lay your own narrow assumptions over the opinion expressed.  I hope you know this.  And (again incorrect assumption) I'm not "dude".