The offside line at a ruck doesn't run through the middle of the ruck as he has indicated, it runs through the hindmost foot of the Lions hindmost player at the time the ruck was formed. It does NOT come forward just because that Lions ruck participant is no longer on his feet!!!
Applying your careful consideration it occurs to me from the evidence of your photo...
The Lions look clearly onside.
The player closest to the Lions in that ruck is clearly a Highlanders player who is on his feet. He is well ahead of the the nearest red shirt we can see in that ruck.
The hindmost Lions player appears to be
in the middle of the ruck.
Ergo according to what you have written and I have quoted ... Those Lions are all on side.
Good call by the ref.
You wanna get your eyes checked Cooky.
Only one of them appears to be working ;-)
Look at the photo, the ref is looking at the halfback. The ball is close to coming out and being distributed to the Highlanders backline, the ref has his arm out. He looks like he has called the Lions line to stay onside and he was happy with where they were at the time he called it, in the split second after that some of the Lions players have anticipated the ball coming out and there has been a tad of 'creeping' from the defending team.
Every team does that, including our beloved All Blacks and as long as it's not blatant, like where a player bolts out of the line way ahead of his team mates, no unbiased referee will ever ping a team for that.
The Highlanders are well behind the offside line, Why? ... because they are attacking and they are expecting the ball. They are a top side, they know what they are doing.
That is standard practice for any good team.
Creating depth so they can run on to the ball at pace.
You need to learn a bit more about how the game is played and focus less on the pedantic approach toward the technical laws son.
Application.
Thats the key.
Now stop whining and make better use of your time. ;-)