I actually view it as even worse in most cases. If you would be loopholing Menadue onto the field anyway without Zorko, then that 80 would be in your team anyway. The Zorko money could be used in a different position to replace an on field rookie score with a premium (a rookie who will probably score less than 80). Therefore, by leaving Zorko out, you can replace a (most likely) much lower rookie score with a premium score.
I think this can be reasonable: Menadue's overperformance makes Zorko a more appealing prospect than what he was when Menadue was expected to score around 60.
Hypothetically: Let's say you are looking for an average of 100 over 22 games (2200 total) from your 543k forward, and you expect Zorko to average 101 over the last 21 games. If you take 101 x 21, he's sitting on 2121: 79 short of the 2200 you are looking for. Last night, you would've said: "OK, if Menadue scores at least 79, he gets Zorko to the 100 average I want across the season". If you add on Menadue's 80, this gets you to 2201, whereas if Menadue had come out and played poorly, Zorko would've fallen short. Obviously, these numbers have been doctored to make Menadue's score last night successful, which is not the best way to make this decision. Ideally, before last night, you would've calculated Zorko's likely average, what you want from him for the season and then used that to calculate what Menadue needed to score to bring Zorko into your team. However, I think these numbers demonstrate the point that Menadue overperforming last night makes Zorko more likely to be successful than he was before the game.
For anyone planning on picking Zorko, I would think of this as a 20 point handicap (starting with 80, instead of 100). It is possible for him to make up those 20 points during the season. But you need to consider, is he a better option than whoever you are picking otherwise, once you account for the handicap? Personally, I think there are cheaper options who will probably score similarly, who don't have this 20 point handicap. With Wells and Kerridge already locked in (and BenKen in most teams too), you can probably only fit a few forward premiums into your team.
Note: this only works if you are not planning on using a FD to get Menadue's points anyway- otherwise, those 80 points are already coming your way, whether or not you have Zorko.