Well, Pyro didn't come to Tony because he thought he was a doctor. Fact, he didn't even know he had a doctorate. John came to Tony because he was the guy in town, and being the guy he had to be the one who was trying to come up with answers for what was going on.
And, if he had answers, wouldn't it be the right thing to share them..? Pyro didn't know. The good guy thing was a new place for him, so he didn't know how to fully operate.
"Frid-?" John perked a brow and then realized that Tony was doing his Tony thing, so he shut up. Pyro sat there silently while looking to his little turtle friend who had been staring up at him concerned. What a good companion. Softly and slowly, he pet the top of Squirtle's head until his attention was brought back to Tony.
"I uh." Pyro frowned. "I don't know. I know it was synthesized to target mutants, but I know it did attack humans at some point." John's face got dark. "I died before the cure was made..." Just saying it stabbed Pyro right in his gut. He was scared and didn't want to die, but he was terrified and didn't want watch Kitty die. "I don't know all the symptoms that people had, but I know it messed with people's powers." He looked at Squirtle. "Poor Squirtle has been following me around putting out my fires all day."