"He'd got no lawful right to change his mind in that way," Dennis told us from Shanghai.
Dennis said Fallows did not answer phone calls, texts or emails, but when asked about the legal battle on Saturday, Red Bull team boss Christian Horner hit back: "Perhaps Ron would have been better giving me a call."
Dennis has now described Horner's attitude as "a bit rich".
"We formally emailed Christian Horner more than two weeks ago, asking him about Dan Fallows' whereabouts, so it's a bit rich for him to say 'Why didn't Ron call me?' now," said the 66-year-old.
"The point is that Fallows has a legally binding contract with McLaren yet Red Bull chose to ignore that and instead convince him to return to Red Bull," Dennis told us on Sunday before the Chinese grand prix.