Glasgow's Sean Maitland and Stuart Hogg were selected along with former-Warrior Richie Gray as the only three Scots in the 37-man squad.
There was disappointment for Glasgow's Ryan Grant who many tipped to be on the plane.
As Gregor prepared for Friday's PRO12 match with Connacht, he told the Herald: "Stuart and Sean will be buzzing and desperate to play in the big games we've got coming up.
"It's great that we've guaranteed a semi and we'll be looking to put our best team out for that. There will be a determination, a confidence and buzz from those selected and there will be an equal determination from those not selected to go out there and play at their best. The Connacht game and potentially Leinster the following week if results go to plan are massive games, away games probably. You can only bounce back whether it's a poor performance or bad news selection-wise by taking the opportunity to have a big game and I'm sure Ryan will do that.
"Ryan's a professional. He'll be disappointed, a number of players playing this weekend will be disappointed not to have made the tour because it's the ultimate for any British and Irish rugby player, but what you want to do is get back out there and play.
"It's great that Ryan's in such good form, we've got some big games coming up and there's a Scotland tour this summer, so he can get out there and keep playing at the level he's been playing at. I had a good chat with him... he wanted his thoughts to himself. It's difficult when some guys are celebrating, but he's very determined to carry on the way he's playing. If there are any injuries – which is likely on a Lions tour – I'm sure Ryan's one of the first names they'll be thinking about to replace the props."
Glasgow hooker Pat MacArthur is sure his teammates will respond positively, saying: "We trained early in the morning so that we could come in for the announcement and the whole team are behind all the boys who are up for it, congratulations to the two lads who were in the team. It is a shame Ryan didn't get in but he will bounce back from that," he said.
"We're such a tight-knit squad, as soon as the announcement was made, we shook hands with those who got in then went over to Ryan and did the same. Then we were straight back into afternoon training and everyone's heads were switched back on to Glasgow."