The 23-year-old warned by the FA for an 'obscene gesture' he made towards Cardiff fans during Sunday's 0-0 draw.
"We received a letter from the FA, talking about Oli's future conduct, which is quite right, I believe," Wilder said ahead of United's match with Arsenal at the Emirates on Saturday.
"They're red hot on that, so for them to take no other action speaks volumes for what it was.
"I've had a word with Oli but I've got no problem with him going to watch Swansea. There's a big connection from him going down there as a young player.
"I think it's quite refreshing at times that he wants to go and watch games of football and be involved in football. We've just had a word with him.
"He didn't really go in camouflage disguise! [His jacket] isn't something I would wear but he managed - in his opinion - to carry it off.
"We have talked to him about how he has a responsibility as a footballer, especially with social media and with cameras everywhere, that he can't get involved.
"He needs to represent himself a touch better and he understands that."