Firstly, he's clearly looking at the EPL as a brand and considering its financial interests only. That is not a viewpoint most of us here share. But from his perspective if your flagship marque is doing poorly, then the fickle fans you mention in Malaysia and places, who have no real affiliation to any club, are more likely to be turned off by the EPL altogether. They are unlikely to start following another team which is not as recognisable or which doesn't have the same kudos.
In the UK, however, loyalty to a team is far deeper ingrained. Whilst Utd's appeal reaches beyond Manchester (as does the appeal of other clubs - Spurs included), most fans are from the city and surrounding areas and those who aren't have often followed Utd for years or do so because their family has done so etc. Utd's support was comfortably the biggest even when Sexton and Atkinson were failing to challenge Liverpool for titles. That was down to the sympathy the club got after Munich. Whilst SAF's success has undoubtedly attracted more fans, the idea that there are huge numbers of people who would jump ship to follow whichever club is winning the league is ridiculous. And it's only been one bad season! SAF went more than one season without winning the league. Many clubs have maintained a strong fan base when dropping down the divisions- as Utd did in '73/'74. Fans of all clubs tend to be very loyal in this country.