FB Creeper Gets Rejected – Leo and Rebecca Buzz Question

Leo and Rebecca Buzz Question - I go to the park and always see this guy. We have said hi every now and then and some small talk. So, the other day I told him.."Hey, I'm not gonna lie , I've been creeping you out on Facebook and social media and I'm gonna send you a friend request". His response stunned me. He said 'Wow, that's actually creepy and don't bother, I would never date you because you did that."
I'm lost for words. Why is that creepy, I was just trying to throw some flirt???? Don't get it!!!