It's not a problem at all, as long as he is willing to have fun on the trails and have a great attitude in the group setting.
But he's your responsibiility if he goes off the deep end or something.
(totally kidding, of course).
Just make sure he has all of the meetup location/time details and knows to bring some food/snacks and beverages, as we'll be spending at least a few hours out there on the trails. Does he have any equipment to air down and air back up? Does he have any kind of comms? Any recovery supplies? This will be a very laid back run and none of those things are really
required, but it certainly helps to not be "that guy" who shows up with nothing and needs everyone's help. I'm sure it'll be perfectly fine either way - if he's not a very experienced wheeler, this will be a great opportunity for him and he'll learn a ton from the group. If he his an experienced wheeler, that's even better.