The drug which is not suitable for patients with acute porphyria for intravenous induction is –
All barbiturates (including thiopentone) are absolutely contraindicated.
There is controversy regarding etomidate because some text books (miller) consider it safe, while other (Lee, Wylie), consider it unsafe :-


Miller (7th/e 1115) has given etomidate amongst the safe drugs.
Lee and Wylie have opinion different to Miller :-

"Etomidate is potentially porphyriogenic in animal models and at least one crisis has followed its use in human subjects, although its safe use has also been reported, on balance, etomide should be considered unsafe".
─ Wylie
"Etomidate should probably be avoided because it is potentially porphyrinogenic in animals, although reports in humans are conflicting".
─ Lee

Anyways, whatever opinion about etomidate, the answer of this question is thiopentone for sure as there is no confusion about contraindication of barbiturates in porphyria.
Thiopentone sodium
Propofol
Midazolam
Etomidate