Etuhu was sent off in the 76th minute at Oakwell after picking up two yellow cards inside three minutes following two adjudged fouls on Kazenga LuaLua.
Ryan McLaughlin came closest to a breakthrough for the relegation-threatened Tykes when his 52nd-minute header struck the Brighton crossbar, while Leonardo Ulloa and substitute LuaLua had the Seagulls' best attempts.
Wilson was happy to take a point following his side's numerical disadvantage in the final quarter of an hour, but was critical of the performance of referee Tony Harrington.
He said: "In the circumstances of having to play the last 15 minutes with 10 men, it was a very good return.
"I think as the game went on I was fancying ourselves to go and win it.
"The (red card) decision was absolute ****. The first booking was shocking; the second booking I'll accept it. The first one put him under pressure; nothing wrong with it, a shoulder charge, he comes away with the ball, he's too strong for the boy, just eases him out of the way. It's not even a foul, let alone a booking.
"I think throughout the game there were lots of questionable decisions which I think everybody was confused about - not just our bench but theirs as well.
"Etuhu was outstanding again today and I felt with him on the pitch we would've gone on to win the game but that was taken away from us.
"The performance was very, very good against a top-quality team in Brighton. We kept them quiet for long periods, we've played some great football ourselves at times, we've created good chances and we've arguably had two of the best chances in the game."
Brighton manager Oscar Garcia saw his play-off-chasing team fail to win for the fifth successive game but said they were the more likely winners.
"In the first half the game was quite even but in the second half I think we were the better side and we created the best chances but we didn't take them," he said.
"I am always positive, I always want to win the game. In the last two games we have shown a lot of character. We didn't play so well in the first half but in the second half we played much better and we created chances.
"This is the way to go and the way to win the games. When the opposition had to play with one man less we put on an extra striker to try and create more chances."
The result left the Seagulls five points off the top six.
Asked if he had a points target to reach the play-offs with six games to play, Garcia added: "No. I am just thinking about the next game."