I just find the idea of holding 2nd graders to the letter of the requirements distasteful. If we want to encourage them to advance, we need to make sure they are doing their best, whatever "their best" may be, to complete the achievements. If, when they are at the meetings, they are involved and participating, then so long as they attend at least "sporadically" (one Den meeting every other month) I'd award it to them. We cannot penalize them for the faults of their parents, whether its work scheduling, family issues, or other activities.
I had 6 Wolf scouts in my den, and like you two (mine and the son of their Tiger Den Leader), earned the Wolf Badge on their own, completing all requirements. As for the other four, two families lost the Handbook and were reluctant to buy a new one for the remainder of the year, one was heavy into sports, and the other had three younger brothers. The two who lost the book I made a list and checking off what we did in the meetings for them, and gave it to them. The sport family and I talked out what their schedule was with me, and kept in contact for the months they weren't there. And the boy with the brothers I just accepted that he kept showing up to the meetings as well as he could. In the last two months of Den Meetings I had "go back" activities that reinforced what was missed earlier (In October we did Achievement 7 and 8, and in April we did an Earth Day service project and earned the Nutrition Belt Loop).
By being positive and accommodating, I got every parent in my Den to also volunteer for the Pack for next year: Committee Secretary, Advancement Chair, Popcorn Chair, and the Sport family and Large family are the Tiger Den Leader and Assistant for next year.
Now, if we were talking Boy Scouts earning First Class, then hold the feet to the fire, point to their handbook, and say they need to get with the program. But with them, they can take as long as they want, they aren't "cut off" at the end of the year. I don't think by withholding the Wolf Badge these boys are going to want to continue in scouting.
In your case, I'd hold a "last chance" double-length Den Meeting on a Saturday/Sunday afternoon or evening for just the boys who need to complete the badge, set up "stations" covering some of the hands-on activities. Ask them if they've "done their best", and if they think they did, then award the Wolf Badge.
And remind them that as they get older, you will expect better adherence to the requirements. But in the Bear year, they will have more input into what those requirements are. For example, they can choose either learning how to safely use a pocket knife, OR how to ride a bike, OR how to fix things with tools. The choice will be theirs.