If you block this mobile user agent, which looks like an Android cell phone, Google won’t be able to see your site at all and won’t index it.
There’s tons of confusion online from people who say that Google won’t index sites that aren’t mobile-adapted – this isn’t true.
Google’s Gary Illyes even posted this on LinkedIn: “Your site can still be indexed in Google Search after July 5, even if it’s not mobile-friendly. If Googlebot cannot access the site at all (i.e., network or HTTP error), the site cannot be indexed in Google Search. This is the way it will be now. The difference after July 5 will be that the site must be accessible to Googlebot’s smartphone user agent. Whether or not the site is mobile-friendly is irrelevant in this case, although it would be nice if it was mobile-friendly.”
“Mobile indexing is not about mobile friendliness. A site can be unfriendly to mobile devices and be indexed perfectly fine. The number of sites that can’t be indexed by Googlebot’s mobile smartphone is super tiny.”
John also commented on Reddit about mobile indexing, saying: “It’s not about mobile-friendliness. Old desktop websites are perfectly fine. It’s only a problem if the site blocks all mobile users with ‘you must use a real computer’ pages – and let’s be realistic, how often have you encountered this in recent years? It’s also not about ranking; it’s about what can or can’t be indexed. Mobile plays absolutely no role at all. I can’t imagine any site made or updated in the last 5 years being affected.”
Source: seroundtable
SEM MasterPlus: Complex website promotion.
SEO
