You have to enable the bacteria to grow first. If you practice proper food safety standards, it won't get the chance.

Also the meat is no longer rare once it's in pho? It goes in raw, but it's sliced thin enough that the heat of the pho cooks it fully

"one slurp" suggests it's a joke among such absurdities as:

serving soup for Halloween

Its beef. Traditional way of pho is having beef slices that are cooked by pouring hot broth over it. It's like having a medium rare steak. The pink doesn't mean its unsafe to eat. I've eaten pho my entire life and unfortunately I'm still alive and kicking