Naked Singularities and the Grandfather Paradox

According to New Scientist, it's theoretically possible, if you can find a naked singularity, to build a time machine. Apparently, naked singularities are an embarrassment to physicists, prancing about with no clothes on and that.

"I don't know why people immediately think that time travellers will be overcome with a desire to commit murder," says boffin Fernando de Felice, referring to the grandfather paradox. This states that you can't go back in time because you might kill your grandfather and thus prevent your own birth.

I think he's got it back to front.

Alex has a rich and powerful grandfather and can't wait for the old miser to keel over and pass on his riches. So he borrows capital against his inheritance and builds a time machine to take him back to the years of his grandfather's youth, neatly sidestepping the security guards in the process.

He murders the defenseless youth, then realises that Grandad hadn't yet made his fortune as the time machine promptly disappears.

But wait! Alex knows a bit about the stock market, so he's able to buy low and sell high when there are large, "unpredictable" swings in the market - which he remembers from his history lessons.

He makes his fortune, marries a nice girl, and gradually comes to realise that his wife is Grandma. Which make Alex his own grandfather. How to prevent his own grandson from going back in time and killing himself?

I hate naked singularities. They give you a sore head.