At this time of the year (spring) snakes are dangerous. In the desert snake bites are rare unlike in the northern part of the country. Scorpions are less dangerous and there were no reports in the last few years, that I remember, about  scorpion bites. Spiders are not a a problem here.

It is safe to hike two gilrs alone. 

We had no reports of snake bites or scorpion bites on the trail. We have thousands of hikers each season on the trail and none has ever asked this quesiton.

But let's consider your friend. There are less than 10 reprots of snake bites / year in the whole country. Beginning of spring is the time when snakes come out of hibernationand that's when they are more dangerous. Fall is definitely safe. 

Enjoy your hike on the INT.

Just watch where you put your foot, don't lift heavy stones or pieces of wood, watch where you sleep, look inside your shoes before putting them on for scorpions, just watch yourself like we do. You'll do just fine.