If the team was going to host a friendly which they wanted spectators at, they would surely find a stadium to use, otherwise what's even the point? At a training facility with a couple of bleachers you'll be able to host what? 500 fans? 1,000? Maybe 2,000? There's two reasons behind teams' decisions to make friendlies open to viewers rather than behind closed doors and they are A) money and B) fan service. With a tiny ground like that you're going to make basically no money and you're only going to annoy the fans by allowing so few in, so it's a double shot-in-the-foot, surely?
I'm pretty sure that when teams host friendlies at their own training grounds, 99% of the time they are just behind closed doors.