by rmsgrey
Some things to consider:1) Until you reach the end of the campaign, you don't know whether something that seems good in the next few games is actually good once you get more perspective. For example, at the start of Season 1, it looks like a good idea to build permanent Research Stations, but if you place all the stickers and then get a win bonus of "build 6 permanent Research Stations" suddenly it looks like a bad move. So long as the first group isn't too far ahead, his foresight is of very limited value...
2) How much do you trust him to be able to contribute without spoilers? Some people, I'd trust to be able to strategise based on what's in front of them rather than on leaked knowledge; some people I wouldn't trust to not leak spoilers if they were kept gagged in an adjacent room...
3) Just from the initial setup, while there's some obvious nudges to do things in a particular order, there's enough opportunity to sequence break that it's possible that you'll be ahead of them on some things even as they're playing later months...
If you trust them to be able to take a back seat and/or ignore what they know, then there shouldn't be a problem - and even if they do know things you don't, the game situation may be different enough that it's not relevant.