Let me correct you. The "thin" mode in Umbra has been disabled due to upgrade to PoSv3 ... It was not a priority and thus will be redesigned inline with PoSv3 in the coming months.
I have followed this discussion and wanted to add that one of your own @kewde stated when I spoke to him about the code, that the 'thin' mode in SDC was broken:

And I just told you the reason. When we upgraded to PoSv3 we decided that there was a much better way to have "thin mode" nodes inline with our future design plans and thus it will not be upgraded as part of PoSv3 but instead later.
I like this that SDC has been exposed. Trying to hide flaws and their incompetence and they had to rely on Monero devs to tell them what to do. They do not answer questions. How do you prove that you sent to a stealth address? No answer, just babble. Why do exchanges like poloniex use standard addresses where with Monero they use stealth addresses? No answer, just propaganda. Get real guys, the SDC team do not answer the questions.
So let me get this straight. Because you are a lazy git with no background in this tech or cred on this forum. You haven't gone through this thread and found the answers to these questions regurgitated by some punk with equal or less knowledge then you.
You feel its not blatantly obvious what a clown you are ( i mean clearly) coming here ranting and raving about tech you don't even understand enough. As though it will somehow discredit the project...and for what? Shits and giggles? A small feel good for you? You're sick kid!
Its all in this thread, go look!... No one is hiding anything. Its boring now when you punters come here pretending to understand the tech and think someone is always being shifty. These concerns have all been brought up and decisions have been made, surprisingly, without you...ouch so sad, such a shame!