This sentence just seems weird to me

I get tweets sent to my phone because I subscribe to various Spanish feeds. I just got this one:

Comer sano no tiene por qué ser trabajoso: preparar esta ensalada te llevará solo cinco minutos bit.ly/2gaO2FF En @ElComidista

I left the link in case someone wants to read the article to get the full context.

So it seems clear they're trying to say,

Eating healthy doesn't have to be laborious: Making this salad will only take you five minutes.

It seems that por qué simply shouldn't be there. Otherwise, I'd translate it as, "Eating healthy doesn't have why to be healthy..."

Can someone explain to me why "por qué" makes sense here? Thanks.