I don't fault him for switching colors. Most who do that are athletes who wouldn't make the team in their home countries, and Gus admits he'll have an easier time doing that in the UK. But at least he has a personal connection to that country, and not just secondhand through his parents - he was born there.
Others have literally sold their talents to countries who gave them citizenship in exchange for athletics. Jamaican female sprinter Merlene Ottey competed for Slovenia from 2002-2012 when she became too old to make the Jamaican team (her first Olympics was Moscow in 1980, and she won a total of 9 Olympic medals, but none after 2000). In Beijing there was a pair of Brazilian beach volleyball players competing for the Republic of Georgia - the little whores even changed their surnames to Geor and Gia, so their names would appear on the scoreboard as Geor-Gia.
If my parents were from someplace like Liechtenstein, I definitely would have been gunning for a spot on their track team.
The only downside I see to Gus's decision is that due to the currently wacky political climate, many will assume he made that choice as an anti-Trump protest. But of course, that assumes Trump will still be in office in 2022.