Groningen 1946: A World Championship Qualifier?

I've occasionally wondered why Smsylov was invited to the World Championship tournament held in 1948. The other invitees had all made their reputations before World War II. Smyslov, born in 1921, started to achieve his results during the war.

I once asked the question on the Forum for About Chess (FIDE rule), and Glenn Giffen replied.

Probably more than anything his +2 win over Reshevsky on second board in the US-USSR telex match September 1945 would stick in people's minds. His other notable achievements were 3rd at USSR ch. 1940 ahead of Keres and Botvinnik, 1st at the Moscow ch. 1945 ahead of Ragozin and Lilienthal, 3rd behind Botvinnik and Keres at the Absolute ch. 1941 and 2nd after Botvinnik ahead of Boleslavsky at USSR ch. 1944. • Soon after the FIDE Congress at Winterthur 1946, Smyslov came 3rd after Botvinnik and Euwe at Groningen in August-September 1946 and then blanked Denker +2 in the US-USSR match in Moscow September 9-12, 1946.

Glenn knows his chess history better than most, and his reasoning was solid, so I left it at that. I was surprised to read the following in Kasparov's 'Predecessors II'.

An important landmark in Smyslov's career was his first international tournament -- Groningen 1946. From the results of the event FIDE determined the sixth participant in the forthcoming match tournament for the world championship (five had already been named: Euwe, Keres, Botvinnik, Reshevsky, and Fine). [...] In the end Smyslov finished third (behind Botvinnik and Euwe), thus securing a place in the match-tournament for the world championship planned by FIDE. (p.272-4)

There is a lot about the World Championship that I have yet to learn, but I thought I was beyond the stage of missing an entire qualifier. What do other sources say?