Am I right in thinking you've not really discussed this with DH, you're just getting fed up with intervening all the time? If that's the case you just need to hash this out properly to be fair, it's a team sport.
Your DH needs to change his behaviour to help you out, either by only WFH when little one is in nursery, or coming up with a plan to be as invisible as possible, IMO you BOTH need to tackle this by working smarter not harder.
There should be a lock on the door, DH should text you if he needs to come out to give you time to distract toddler, not just spring out after you've been trying to deflect a tantrum for half an hour.. that is such a dick move. I know you've heard it throughout the thread, but you definitely need to firm up with little one.. you can't negotiate with terrorists toddlers, but you do need to find a solution that works for them, distraction, rewards etc, losing priviliges on tantrums, etc. IMO I don't think you should ever let your DS see your DH when he's 'working', and that way he'll learn that no matter what he does it doesn't get the result he wants so you both need to be on top of that, he will learn if given the opportunity.
Our DD is 2, and she has almighty tantrums at times, but I can reason and explain things to her for the most part.. If i just said no, or stop it, it would be a full on meltdown, but when she does have a tantrum about something, I tell her to listen (have to repeat 'listen' 2-3 times sometimes if it's a doozy), then only when she's stopped screeching I explain that she 'can't do that right now for whatever reason applies' we can do it 'later', BUT we can do 'this!' instead right now (insert something she likes) she understands what later means now, and we always do that thing later, use the lack of attention span as a tool if you can!