That’s what the billionaire is saying to reassure investors about his interest in the biotech. “If an offer was made, Elan would not activate its change of control provision,” for the Tysabri multiple sclerosis med, Icahn tells Bloomberg News. “I don’t think they wanted to be a poison pill. That’s very important. It opens the door a lot.”

On Friday, Biogen put itself up for sale after investor Icahn made an offer and the biotech claim to have received “expressions of interest” from others. Icahn offered $23 billion last week and believes Biogen, according to Bloomberg, which notes that some analysts project Tysabri sales could exceed $2 billion in three years. Based on its market cap as of last week, Biogen is worth about $20 billion.

Over the weekend, Elan hired Lehman Brothers to help consider options on the Biogen agreement, including restructuring the contract, selling its stake or buying out Biogen’s stake. Another option is to leave the pact unchanged. The Irish drugmaker’s options also include the possibility of working with any Biogen buyer, according to Biogen spokeswoman Naomi Aoki, Bloomberg reports. She declined to comment further.

Biogen should be an attractive target for large drugmakers that are faced with generic competition, Icahn says. “They’ve got a tremendously valuable pipeline that’s gone unnoticed,” Icahn says, adding that “Elan told us they would not stand in the way of an offer.”

Separately, the FDA extended its review of Tysabri for treating Crohn’s disease by three months in order to analyze a risk management plan, Bloomberg adds.