Have the gnome modify it with a pogo stick attachment.
I thought the Desert Strike would follow that rule too, but I was wrong. You'd think a sniper system made for harsh conditions would be durable to jostling as well.
Zomby-ing this point a bit, bu it's something that's come to my attention recently, and wanted to say my piece.
The last errata I've seen for Arsenal came out before the anniversary corebook made this (bad/pointless) change, so there's no reason to think another military rifle like the Desert Strike (or the M121, for that matter!) would be built just as well.
Really, the two snipers in the corebook represent the two main stereotypes of a sniper: the mysterious assassin in the bell tower, calmly putting his gun together from it's nondescript briefcase while his target gives a speech (SM-4), and the expert combat marksman, taking out enemy baddies from great distances while right alongside his fellow soldiers (MA-2100).
Frankly, I think it made a WHOLE lot more sense when the Ranger Arms SM-4 had the whole "made of tinfoil" problem as a specific drawback to being able to be taken apart and put in a briefcase.
If you plan on keeping with the anniversary rules, I'd recommend modifying them so that the -1 is non-cumulative, and only applies to extreme range targets (if an assault rifle's sights can stay lined up out to 500m through a running firefight, so can a sniper rifle's). I also see no problem with ruling that the Desert Strike and M121 from arsenal are built just as ruggedly as the MA-2100.