I would say get him some plants, I bet he'll appreciate it and it'll be a nice addition to the tank. Plastic can work too, you just have to be careful. I can't imagine he would pick on the snails though, and I would give him time to adjust, he may just be curious at first and the snails will close up if he gets nippy so I doubt he'll do serious damage.
Prince (HM betta)
Cetus (CT betta)