Can I support a 18' tv between two studs?

We are building a new house and I want to put a small TV in our bathroom. In order to center it on the wall I would need to put the TV directly between two studs | tv | Is it possable to add a 2x4 inbetween the two studs behind the drywall to support the tv or will it jsut pull out? |--| My contractor seems to think it will just pull on the drywall and wants me to put a piece of plywood drectly on the wall.