Agreeing w nearsouth (TYVM) post -- the outfit disguises SP's gender, or at least leaves SP gender open for discussion.
Annnnnnnnddddd the outfit also offered other benefits to SP.
As others posted earlier, the head to toe outfit gives coverage that helps reduce chances for SP's DNA to be left behind by SP shedding skin cells, head hair, arm hair, etc.
As others posted before, if the outfit is padded or has body armor features, and if SP & MB - or anyone - got into a physical altercation, padding/BA would help reduce chances of other person leaving bruises, cuts, swelling, etc on SP's body, observable by LE, fam, friends as evd of involvement.
'All that trouble?' In planning a break-in (for what-ev original purpose was, whether stealing church prop, robbing anyone SP might come across, verbally confronting MS specifically, physically assualting MB, killing her, or ????) SP might have assessed above advantages as outweighing poss disadvantage (spending $ on outfit, outfit hindering gait, etc). As always, JM2cts, could be wrong.