Lennox knew Alistair's intention and had been busy ensuring Huayi was safe from Alistair's underhanded attacks. However, he was more worried that Alistair would turn his attention to Adrienne and go after her instead.
When Adrienne confessed that she remembered her past life and how she lived miserably because of the Jiang family and Alistair, Lennox didn't doubt her claims. Instead, he felt her confession shed light and cleared out some of the mysteries surrounding her.
He also had to admit that her knowledge about the future had given him and Huayi a great advantage and that they had earned a lot of money. Lennox owed Adrienne a lot and wanted to show his support in any way possible. She also helped him and Gavin avoid mistakes when investing in risky ventures, ultimately saving them from the financial ruin of Huayi.