Equity Research and the Investment Banking Division are completely different groups with procedures in place to make sure they never interact with each other.
I asked a banker this exact question back then. All I got was flowery language of great walls and reputational damage.
We all know what happened. The bubble popped. The two sides don't need to talk. The equity research is public. Incentives are such that both sides want to pump.
[1] https://www.finra.org/rules-guidance/rulebooks/finra-rules/2...