The London Olympic Games will be Giggs' first chance of appearing at a major international tournament.
Blackmore told the Manchester Evening News: "Of course, it is brilliant for a player of Ryan's stature, who has not been able to perform on a big international stage like the European Championships or World Cup for Wales.
"We've missed out agonisingly on a couple of occasions.
"Ryan would have deserved that platform but this is a great honour and a great opportunity for him, but I still think it has been a football decision. Giggsy is the hardest player I have ever played against.
"As a full-back facing him in training for United it was torture. He was so elusive. Fast, tricky and great balance. It was a nightmare for a defender.
"Twenty-plus years on and I still think those attributes are there.
"Yes, he has reinvented his game a bit, but at times he still has the pace to go past a man.
"He has the ability still to open up a game. That's just the sort of player England were missing at Euro 2012. Giggsy is still very effective."