Because Grealish is a top player and they want him? Because by letting the player know they are interested they are more likely to get him?
That's about getting their man, not destabilising us as a club. If anything it shows that they see us as insignificant, a feeder club, not a threat. We can show real intent by moving heaven and earth to keep him. Then we can be a threat to City in the future.
If we swagger about thinking we're within a country mile of being on a par with City even within a 5 year period, then we will never get there, because we have failed to understand what we do realistically need to improve.