"unreasonably so" is a correct and usable phrase in written English.
It is often used to express strong disapproval of someone who has acted unreasonably. For example, "He demanded an unreasonable amount of work to be done in a very short time, and he was unreasonably so in expecting it to be finished quickly."
Not unreasonably, so did Steve Brookstein.
"This gets a lot of airplay, but unreasonably so," said Gerard Finelli, principal of Colonial Elementary School.
A taxi driver in Bad Hersfeld, who did not want to be quoted by name because a close relative is still employed by Amazon, said he had worked as a picker one Christmas season and found the work demanding but not unreasonably so.
In an open letter to "fellow Manchester City fans", Mansour said: "We are ambitious for the club, like you, but not unreasonably so and we understand it takes time to build a team capable of sustaining a presence in the top four of the Premier League and winning European honours".
PB: Valuations have gone up over the last 10 years [since we launched True] but not unreasonably so.
For example, move-over residuals (for reruns on the Internet) are very low, and it seems unreasonably so.
While the price point was spectacular for the quality (I saw beautiful dresses from $400 - $2000, nothing was priced unreasonably--so refreshing) RK's selection seemed too "pageant-girl" for my taste.
About half of the cases fall under the heading of a broad category called unreasonable behavior, in which one party has to accuse the other of acting so unreasonably that living together has become intolerable.
Not merely wrong, he adds, but unreasonably and unjustifiably so.
If they do so unreasonably, they may find themselves coming unstuck if challenged.
"The reaction to him was always hostile; people wondering how a smart, grown man could be so unreasonably angry about games".
