In addition to being offended by this notion that anyone who is married to a convert is in the same category as someone intermarried, there is more that bothers me.
I am bothered at this notion that assumes a convert will take the kids to the grandparents for Xmas and Easter. Personally, most of my family is deceased. Actually, we were small to begin with. However, if I had family, the solution would be to have spend Thanksgiving and/or July fourth with my family and eat kosher. If I didn't have space at my place, we could go to a restaurant or I could bring the food and a plug in blech to the relatives to reheat the food. You would use the disposable stuff that people use on Shabbos anyhow. Fourth of July is easier because you can buy kosher food (hot dogs, burgers, potato salad, mac salad, potato chips etc.) If it's hosted at someone else's house, you can buy a small cheap grill and bring it with you.
Some people invite gentile family for Jewish holidays. I think that would create more problems, especially with Passover where the kosher restrictions are more than the rest of the year. Perhaps the gentile family could come for the seudah mitzah on Purim. I actually think Chanukah would be a bad idea because their non-Jewish cousins would be talking excessively about Xmas.
Which brings me to another point, one should be prepared to explain Xtian holidays to Jewish children. This would be more of an issue for children of intermarriage, a converted parent and Jewish children in public school. However, I have seen it come up with Orthodox Jewish day school children whose parents are both Jewish from birth. After all, there is all that stuff in the stores. Personally, I would tell them that some people think G-d became a human, which is silly. Xmas is when they think this person was born. Easter is when they think he died and came back to life. It's that simple.