But Kellock is adamant fears of a mass exodus from Scotland are unfounded and told the 22-year-old to knuckle down for the remainder of the season at Firhill.
He said: "Richie knows he has got a big season ahead of him and he wants to leave on a high.
"I am disappointed he is going on a personal note and for Glasgow. These things happen - it is professional sport and he was always going to get offers. I think Richie was always going to get offers from all over Europe and he's made his decision.
"I hope it's a good decision for him but there are things happening in Scotland.
"The new Scottish Rugby Union chief executive Mark Dodson has come in and made exactly the right noises, the things the players want to hear.
"It is about what we do this year and not about where he is going next year. I believe that this time next year we will be a stronger team than we are just now."