You've clearly identified some of the concerns & potential issues. Each situation and person is unique and you know your husbands workings better than anyone.
As long as you can stay emotionally unattached to the issue itself and keep being observant & analytical you can make it a no-harm exploration. And in the end, everyone will know each other and themselves better.
There can be a lot of reason as you alluded for someone to be attracted to new sex partners. Some are pretty valid & harmless. Other can be more concerning. (emotional health) It isn't the "desire" in and of itself that warrants big conversations - it's more the "why" of them.
Unlike some poly couples, in our relationship we acknowledge the place for "sex only" fun in our lives. Sometimes it's for no better reason than variation. Sometimes it might be for a particular fantasy or itch that we maybe can't scratch as well ourselves. No big deal. But if it were to become some compulsion that caused complications in our relationship, we know we can sit down and hash it out.
As far as the objectification, I think that door swings both ways. And I know there are people emotionally intelligent enough to be able to slip in and out of being "objectified" without damaging their psyche. We are both that way. But we have fulfillment outside that model so it doesn't present such a threat. That debate to me/us is largely philosophical anyway. Other are more fragile.
So in a nutshell, exploring may be necessary anyway in the long run. Just be awake & sensible and keep talking !