I believe there was an investigation... From the first article that came up:
“None of the results or findings indicated that food poisoning was the cause. The likely cause of illness suffered by the Tottenham Hotspur FC staff and players was from a viral source.”
I'd still be suspicious, wonder if they just checked for naturally occurring bacteria by poor food hygiene standards or whether they also looked at possible deliberate contamination.
It seems unlikely so many players would catch a virus and be at peak symptoms at the same exact time.
Football teams spend a fortune on sports scientists, treatments and supplements, it's not inconceivable that our fiercest rivals had someone with some expertise go rogue when they saw an opportunity to weaken our chances.