Plus, it serves as an income stream for him. Be thankful he, and the entire team, are as dedicated to XC as they are. Go look at other coins whose devs quit or just go missing. I have seen coin communities try and raise money to pay their dev, or hire a new one to make algo changes in hopes of saving their slowly dying coin.
This is another good point. It's quite selfish of the community to feel that Dan shouldn't work on other projects if it may benefit him personally. Nobody here is paying him for his time. I would be curious to know how many people that complain about him spending time on other projects have donated to the XC team. I'm sure he's logged countless hours.