Would have absolutely made sense for the Nets. They lack scoring. Simons and Thomas are both combo guards so they could be at either guard spot and offer better switching. Let's face it them switching is better than getting caught on every screen for them. That trio of Simons, Thomas and MPJ would have given them a good mix of offense enough to actually compete for playoffs.
As for salary I already mention not signing the duds before, that would have kept team under second apron and maintain KP.
The biggest issue by all reports is the C's want to fully reset and save money getting under the tax altogether. They still plan on moving Simons as a salary dump. So trading for a big is a moot point anyways as they don't care about this year. If they cared about this year they would have kept KP and moved Simons.
I disagree with the first part, you do not mask a terrible guard defender with another terrible guard defender, that just makes the situation worse. On the whole, I do not believe Simons has any real value to a contending team unless his salary is around the taxpayer mid level. There was some talk of basically getting for Simons what you got for KP - that was not a possibility. KP has value because despite his constant injury status, he is over 7 feet tall with value on both sides of the ball in the most meaningful ways - elite long distance shooting and rim protection. There are maybe a half dozen or so guys in the league who bring what he can when healthy (huge asterisk). Simons brings long distance shooting but negative defense and is a smallish guard by current standards. It would and will be near impossible to trade him for just a salary under 8 figures (like Niang).
But I am more interested in the last paragraph you wrote - what reports are saying the Cs want to get under the tax altogether? They would need to chop $18 million in salary to get there and have not made a serious move in a month. If they were actually trying to get below the tax level, the move is / would be to trade Jaylen. I hate losing Jaylen but it is hard to get below the tax level when you have almost 90% of the cap committed to three guys and one of them - the actual super max guy - will not be playing.
I fear that the Celtics will have a hard time returning to title contention with so much salary tied up in Brown unless they nail a pick or two. But since the Celtics have chosen not to go that route, I do not see how they can be expecting to get below the tax absent buyouts / waive and stretch. So I have a hard time believing they have been operating with the goal of getting below the tax. I think they just wanted to get below the second apron. They did that and now are just quiet.
To be fair, this was a difficult summer to drop a ton of salary because nobody had meaningful cap space except Brooklyn so there was no opportunity to, say, dangle White to a team with cap space for just picks. And now that much of the major offseason action is done teams are settling in to what they have and they have less - not none, but less - wiggle room to take on a lot of extra salary. That will make it harder to get below the tax if the Celtics find themselves as a .500 or worse team in December / January. But maybe the hope is that at some point a team in contention is willing to take on an extra $5 to 7 million in short term salary (and maybe they happen to have $20-24 in expiring contracts) to add Simons for nothing of substance. And maybe a contender has retained their taxpayer mid level and hard cap space and can acquire Hauser for a couple of seconds or maybe even a late first (I doubt that and do not expect it). And that might get the Celtics close enough to allow one more move that could get them under the tax level. It is just harder to see now, so I have doubts that the front office ever really looked at getting below the tax altogether.
I do hope I am wrong because I see little value in being a bottom tier play in candidate in a very weak conference, I would much prefer they take their chances in the lottery to have a better chance at nailing one of those draft picks they will need to nail to extend the Tatum-Brown competitive window. And if they are doing that, I would rather have at least one year below the tax so they can better decide how to proceed next summer.