bro, normally tyre shops buy tyres getting of from brand new cars, tyre storage is a big expense if u consider, i have seen tyre shop not willing to take old tyres even for free as its just hassle for them to manage them, and u never goto gud tyre shop to look for old worn out tyres.
for ur satisfaction u can do a visit and ask around from the new tyre seller abt that.
and how u gonna check for punctures without taking the tyre of the rim? its he standard practice, so just chill out.
next time u can try selling ur old tyres on fcbk/olx.or pakwheels.