My friends and I got mixed up in a similar group our freshman year of college. I grew up a faithful Catholic, but entered college without a true understanding of what makes the Church so special and unique. Ended up joining this weird group after a member advertised a Bible study to us. Like your friend's group, these people also tried to quickly baptize new members into their church. My one friend and I made it pretty clear that we were Catholic and did not require any further baptisms, but my Protestant friend got a lot more pressure from them to convert. The whole feeling of the group was weird, and though nobody bothered me too much, they were definitely trying to control the dating/social lives of members who were more involved. Eventually we told them we were done, which was a big dramatic thing for them. We later found out from another guy, who left the group a few months later, that the church leaders actually spread rumors about my Protestant friend that were absolutely untrue, just to frame it like she was evil & sinful for leaving. It was completely ridiculous - telling people "she gets around" even though at that point, she had never kissed a guy in her life.

Anyway, sorry for the rant. It's a good thing your friend picked up on something fishy. Most Protestant groups are NOT like that, so don't live in fear of them all. This was an extreme circumstance, but there are a number of legitimate, well-established Protestant organizations that hold Bible studies on college campuses, if that is your friend's interest.

After my experience, I was definitely a lot more wary and ended up getting involved with FOCUS and Newman Center. I'm not sure how big your school is/what Catholic groups you have around, but maybe encourage him to come along with you to their events? I was lucky in that there were a few major universities around that shared a rich Catholic community, but I imagine that it can be frustrating if there is not much going on for people your age.