they will keep laying and it will stress the females' bodies. I have a 6 year old female and one of undetermined age that both still lay (I'm assuming duds since they have not been with a male in a long time, and I don't bother to try to incubate) most herps are not communal. If anything, he's just feeling the urge to procreate.
I would check into why you think your females are looking thin. Both my ladies are quite robust and (dare I say it) chunky... are they getting enough food without competition? could they have picked up worms from feeders? are they just more active and could use a higher intake? Or are they just a healthier, more lean weight since you stopped breeding them?
maybe just re-doing the male's terrarium would help you feel better about having him separated? Also, if I recall correctly, you have the male in a 10g? If so, he would likely appreciate more space, and it would give you something to change up.