that's exactly the questions I asked in their thread, glad you posted a thread to discuss it. thanks.
I have this question myself for some time, I saw your message in their thread. It's better have a separate thread to discuss it.
I would suggest you look at XC's Dev, Dan Metcalf's resume, and see that he is quite capable of what he says. Also, you will have a nice shot at a very nice bounty very soon with the 3.0 release and a look at the whitepaper coming out soon.
Resume does not mean anything, do you know satoshi's resume? People put all bullshits in their resumes. If the XC truly supports multisig, just show a multisig address as greenclover asked. Very simple.
If you ask me whether Mammothcoin / supercoin's supersend really support multisig or not, I can show you their multisig address/tx in 10 secs, very easy. So don't talk garbage here, show the facts.