My apologies to @Chocolate for continuing to nag about this question (or if I've misunderstood your comments).
According to the link it is unnatural (ungrammatical?) to say:
1) 就職しないと心配する。 where と is used to mean 'if'
If I don't get a job I'll worry.
Instead, I should say:
As I understand it, the reason that using 心配する is wrong is because there is no object.
However, this sentence is fine:
If I don't hurry home my parents will worry.
This sentence is fine because there is an implied object: 親が私を心配する. My parents will worry about me.
But I'm struggling to see how sentence 1) and sentence 3) are fundamentally different. Why can't there be an implied object in 3) which might be 就職できないこと?
I'm happy with sentence 2) but is 1) completely wrong or just a bit awkward (ignoring, if possible, the fact that you normally might/will treat と as quotative)?