Although I appreciate that in your specific instances modifying for mobile maybe overrated, since MOST other websites have mobile traffic 60%+ IMO for most it would be foolish to ignore
There are two different issues here - catering for your visitors ... and catering for Google.
With respect the first, don't let any Catt Mutts tell you what to do! Know your market, know your visitors, test, improve. End of.
With respect the second, don't do it. But if you do, don't let any Catt Mutts tell you what to do. Know your market, know your target, test, improve. End of.
As an aside, if a large chunk of your traffic is coming from Google then you're doing something drastically wrong! Yes, wrong. Google, despite its size, accounts for less than 5% of how people reach destinations on the internet. The others are social media, by following links on other sites, by clicking links in emails, by following bookmarks (which is probably how you arrived at UKBF today) etc. etc.
If you spend too much time and money chasing "free" Google traffic you're simply building a vulnerability. Sure, free organic traffic is the easiest to get. But it's also the worst kind in many ways.
TL;DR: Don't worry too much about mobile SERPs, go do something useful instead
