Oh, reb Toi i forgot to mentions that the rif and the rosh both bring down the halachos of techeiles even though they never bring down halachos that are not nogea bizman hazeh.
Now let us Hondle the biur hagra you quoted earlier.
The Mechaber In Orach Chaim Siman 9 Sif 2 says ????? ?? ????? ?? ?? ??? ????? ?????? ??? ???? ????? ??? ??? ????? ???? ?? ?? ??? ?????? ???? ??? ????? ???? ???? ??? ?????
The Biur hagra on the words ???? ??? ????? ???? says ?’ ?”? ?’ ??? ?????? ??? ??? ??? ???? ??
We can probably all agree that the gra does not quote a medrash to ”prove” the mitzious that we have no techailes today. Everybody knows that the gra tells us his opinion in a few words which normally is just a mareh makom. So what does the gra mean?
Well, The Gra tells us to look at the Medrash. So let’s look at it. The lashon is like this
??? ???? ????? ??? ????? ????? ?????
????? ????. ????? ??? ??? ??? ??? ?????? ???? ???? ???.
The Medrash says the mitzvah of tzitzis is to put on lavan and techeiles. When does this apply? when there was techeiles. But today we only have lavan because the techeiles was nignaz (forgotten) so the mitzvah is with lavan.
All I think the gra is saying is that when you do not have techeiles their is still a mitzvah with lavan.