yes.... thats EXACTLY what that says... but i will expand...
REGSHO ONLY encompasses FTD's that are cleared through the DTCC... any proprietary trades made between MM's on an EX-clear basis are NOT reported to regsho and thus DO NOT appear as FTD data...
when a MM would like to 'make money', they can hide behind this proprietary trading strategy excuse and choose NOT to report any ftd's between other friendly MM's...
we could go on of course, but you already understand the mechanisms... i and others have explained the mechanisms ad nauseum here.