If tomorrow America says we going to make nice. Truly welcome Chinese investments, China is going to say no?
For starters. China never forbid it in the first place. You forbid the existences of Chinese entities, which is exactly why what you want isn’t going to work. The business environment does not exist for Chinese investments to be viable in the US.
If the US welcomes Chinese investments then what is there to say they won’t outlaw it over again in a few years. Businesses do not operate on a the basis of a promise. They operate on the basis of reliability, stability, and trust. Neither of them exist. Investments and ventures are long term multi year and decade projects.
Trump can welcome it as much as he wants but Congress is bipartisan anti-Chinese. If you want trust to be rebuilt then Congress must start revoking anti-Chinese decrees. That isn’t going to happen. Trump could suppress the will of Congress for at most 1-3 years and then it becomes unpredictable.