The Uziel only has Large Weapon Pods on the arms, it can't carry Assault Size weapons there. RAC5 is an Assault Size weapon, RAC2 is Large.
Well, as to design philosophy I have a simple maxim......MWLL doesn't have to conform to CBT, but everything MWLL must be explainable in CBT or it's cheesy. As well as this, anything that moves to far from the stock CBT chassis description (assuming all machines are omnis for MWLL sake) is a mistake in my eyes too (but I don't mind tearing out the JJs, as this is a time and tested refit practice), so engine, internal structure & armour levels are kept to give us the "omni" chassis to build from.....hence 20tons (loosing JJs takes the podspace up to 23tons IIRC).
So while you may have an Uzi that can't fit RAC5s in it's arms due to weapons pod size in MWLL, you can in CBT, as the RAC5 is only 6 crit spaces, and as long as you store the ammo & CASE in the torso you should be fine on space. And conversely, while you can have ridiculous configs in CBT, all MWLL configs must conform to CBT rules (or they will never work correctly).
So if the Mauler in CBT had to keep it's UAC20s in a torso pod, then the criticals of the UAC20s would be split between the torso & the adjacent arm (in a CBT build of the same machine), and sure. while this conforms with CBT I'd definately call it cheesey(it might be do-able in CBT but it's the thin end of the wedge for realism). However, if that Mauler fits those UAC20s into the arms (dependant on arm podsize of the Mauler in MWLL) then this is not cheesy, as this is ALSO plausible in CBT (you can build this 'mech in CBT without splitting the UAC20s between 2 locations each), and so we've gone from cheesy to golden if the pod system works IMO....that's the point of the pod system surely....to add restrictions to CBTs free-style uber-builds to create distinct 'mechs?
PS. I think my Uzi with GECM, 6 Medium lasers, MRM30 & 1 ton spare ammo would be fine in MWLL, 3 Medium Beams in each Assault pod, why not, they're 1 ton and 1 critical slot each (4 might max the pod maybe)? It's a design to maximise the Uzi's brawler potential.