The point was you wanted a proof that Robert's actions depend on whether Lena sleeps with him or not. And it's right there, in the game script. He also has, evidently, some degree of impact on how long Lena keeps her job. It does make a difference whether Lena gets to work for a while longer or not, as a result of Robert's action or lack thereof. At least in the discussed context of Robert having impact on Lena's ability to keep working (if for a few weeks longer) at the restaurant.
You might view it as perfectly reasonable, i view it as bullshit excuse. "Samantha overheard the chief of staff isn't pleased with the trouble you've caused" isn't some sort of state secret, and no one would give two shits about such reveal. Robert isn't being cautious, he's just withholding the info to get Lena where he wants -- to the bar where he then tries to get her drunk instead of actually tell her the thing he was oh-so-cautious not to reveal at work.
I don't like Robert based on him demonstrating himself to be a shit character who tries to pressure Lena into something she has repeatedly told him she isn't interested in, and on his displayed attitude of the "nice guy" who is in reality anything but. Neither Perry nor Wade act in the manner Robert does, so i definitely disagree these three are somehow on the same level. Perry is clueless and socially stunted, and Wade is lazy af (potentially depressed, idk) while Robert is genuine creep.