Since they have different part numbers, it's absolutely
an issue of Fiat not being able to offer the Abarth wheel without dual certification.
For them to be able to sell the Abarth airbag assembly over here, they would have to go through the process of obtaining PSW (parts submission warrant) approval to ship it here. That would involve PVTR (product validation test report) and several other tests ($$$). Fiat apparently assume that the Abarth will sell in low enough volumes over here that the ROI isn't worth the investment, OR they would rather promote Fiat over the Abarth brand (for reasons unknown). Other markets (AUS) are only
getting the Abarth, so there's no double-investment to avoid. They PPAP'd the single part for the Abarth, and called it a day. For the FED/US market, they only PPAP'd the Fiat-branded airbag assembly. I don't foresee this changing unless Abarth sales remain strong into the next model year. FCA are very cautious to invest in US-market niche cars after the failures of several previous FCA sports cars (and the lackluster sales of the rest of the Fiat brand, quite frankly).
They only way US owners are going to obtain the Abarth logo is if FCA decides to list the badge as a separately serviceable part number (for example, if UK owners start scratching theirs and want to replace just the emblem w/o full airbag replacement). At that point, it would be feasible for US owners to obtain the logo because it's not HAZMAT, and could easily be shipped across the pond for use in a FED market. Expect to still pay something crazy like $100. For reference, the european-only Crossfire SRT-6 badge (slanted font) was eventually made available through US dealers, but it was $150 (supply/demand).
Even something as simple as an emblem needs PSW approval for clearance through US Customs, but an emblem requires far less testing and certification than an airbag with a built-in explosive device.
Source -- I work in the automotive industry, in international sales & logistics