Three-check rules incomplete?

When playing three-check, I came across an interesting situation:

I already gave check twice, and my opponent just checked me for the first time. However, I was able to check him for the third time and win the game, were not for the rule that you have to get out of check first...

A bit of a clumsy rule is it not?

>The winning move has to be legal, e.g. you can not give the third check while in check.

lichess.org/variant/threeCheck

You do have to get out of check first. Seems fine to me with the idea of following FIDE rules

In normal chess you can't check or checkmate while you are in check either.

I understand the point a bit. In Atomic you can capture the oponents king while beeing checked. But three check is more similiar to ot standrad chess than atomic, so i think it is consistent that you have to take take of your own checked king first.