Google argues the Huawei ban would hurt its Android monopoly
The Trump administration would probably describe its Huawei export ban as a move that improves national security by keeping China's pet telecom company out of the US market. According to a report from The Financial Times, Google's recent discussions with the US government actually argue that the Huawei ban is bad for national security. Google is reportedly asking for an exemption from the export ban.
The argument, reportedly, is that Huawei is currently dependent on Google for its android smartphone software, and that dependence is a good thing for the US. The Financial Times quotes “one person with knowledge of the conversations” as saying, “Google has been arguing that by stopping it from dealing with Huawei, the US risks creating two kinds of Android operating system: the genuine version and a hybrid one. The hybrid one is likely to have more bugs in it than the Google one, and so could put Huawei phones more at risk of being hacked, not least by China.”
Today, non-Google Play versions of Android exist in China, but it's rare that any of them are significantly different from a Google version of Android beyond the pre-loaded app selection. Chinese manufacturers are still global smartphone distributors, so they all build Google-approved Android OSes for the non-Chinese market. What usually happens is that a single OS goes through the Google testing process, then it gets split into two versions. Internationally, it gets the Google Apps; in China, it gets a China-centric app selection.
So while these Chinese Android OSes are still technically Android forks, because they don't ship with Google Play, they are not that different from Google-approved Android. Google's control over the Android ecosystem even when devices don't use the Google apps means there is still some level of security and updateability going into these devices. Google's first argument in that Financial Times report is that more secure devices are better for national security.
The second argument in the above quote is that a ban would “create two kinds of Android” and hurt Google's monopoly over Android. If you're a smartphone manufacturer looking for a smartphone OS, Android is the only game in town. The latest worldwide OS market share numbers from the IDC show an 86.6/13.3 percent share between Android and iOS, respectively, with “Other” clocking in at 0.0 percent market share. Taken as a whole, the US has a smartphone OS monopoly.
For companies that aren't Apple, it's Android or nothing, and Google controls Android, both the direction of the OS itself and the OS' app ecosystem. Weaning Huawei off its Google dependence would theoretically lead the company to create some kind of viable, China-powered, China-controlled Android operating system that would then be distributed to the rest of the world. Android is open source, so there's nothing stopping anyone from doing this now, but part of Google's control strategy is to create tools and updates that are so good that no one wants to compete with them. Cutting Huawei off from those updates would force that company to create a competitor.
Banning Huawei from dealing with US companies is definitely a double-edged sword. Huawei would have a tough time building smartphones or an app ecosystem without the help of US-originated technology and app developers, but US hardware and software companies would lose access to the second largest smartphone maker in the world.
Really, the two outcomes here, if the export ban holds up, are that either (1) Huawei can't handle the export ban and shuts down, like ZTE did, or (2) Huawei weathers the storm and rises as a rebuilt, fully US independent smartphone company. Google's argument is basically along the lines of that old saying, “Keep your friends close and your enemies closer.”