While your post may appear selfish and a bit hipocritical at first (having your own kids but hesitating if a guy has his own), that kind of blunt honesty is what all those kids deserve. At least you are thinking about the fact that he has kids, rather than not giving it any attention, which is indeed selfish. So I don’t fault you for your view for that reason.
When I dated, if I met a woman with kids, I would not want to meet those kids until I felt it could be serious. Single moms are sacred. I would never just casually date a single mom. While I think you are dating her AND her kids, the risk of they becomming attached to a surrogate parent (depending on whether their dad is still in their lives) is significant. If it became serious, then I would need to realize that I am entering a relationship with them just as much as their mom. Some people are not ready for that, whether they have their own kids or not. Step parenting is no walk in the park.
If I were a single dad, and a woman hestitated if I had kids, I would want her to tell me and move on and would appreciate her for it doing so.
TG’s approach is a very noble one. Not many people can do that.