Selections elsewhere suggest, though, that, given the lock's eagerness to lead his side whenever possible, the timing of the injury may have been a silver lining for the management as they seek to ensure their captain is fresh for the much more important matches to come.
It may be a sorry state of affairs that, at the halfway stage of the Heineken Cup pool campaign, Glasgow's focus has already turned to the more prosaic matter of their defence of the 1872 Challenge Cup in the festive derby meetings with Edinburgh.
That, though, is the reality since, out of contention as they already are for even so much as a consolation place in the Amlin Challenge Cup quarter-finals, all they have left to play for in Europe is to avoid a bottom-placed finish of their pool for the first time in seven seasons, which at least partly explains the latest reshuffling of the team.
The real clue to priorities ahead of the derbies lies in the absence from this weekend's squad of Henry Pyrgos and Stuart Hogg. Meanwhile, as his sometime rival for Scotland's No.12 jersey Graeme Morrison returns from injury on the bench, Sean Lamont, the fourth Warrior who was in Scotland's starting line-up for the last of their autumn Tests, returns after having his rest last week, albeit he does so in the unfamiliar position of outside-centre.
Sean Maitland, the signing from Canterbury Crusaders in whom so much hope, as well as money, has been invested makes his first start at full-back as the constant rotation of stand-offs, meanwhile, results in Ruaridh Jackson, left out of last week's squad altogether and sent for match practice with Dundee HSFP in the British & Irish Cup, is recalled once more while Scott Wight and Duncan Weir drop out this time around.
Naturally, Gregor Townsend, the head coach, maintains that the selections are all about finding combinations that can surprise Castres and produce what would now be a major upset in the context of this season's competition.
"It would be a great achievement to go out and win in France, but we've selected a team capable of playing a high-tempo game, which is what we'll need to do in order to beat Castres," he said. "We have some very dangerous runners in the back line, five of whom have played on the wing this season. There is pace throughout the side and I'm also looking for a hard edge from the forwards.
"We must be much improved in our accuracy from last week's performance, which was well below the standards we demand of each other. It wasn't a true reflection of what this group has produced this season."
That is as maybe, but it was the third successive match in which they failed to register a try, which means that, taking into account the two-week lay-off during the autumn Tests, they have not crossed the opposition line in more than a month.
Rediscovering how to do so is a must ahead of those derby matches but, with Castres having lost just one match since September – that was at Ulster, the only team in Europe with a 100% record this season – while the French side has been strengthened since last week's win at Scotstoun, achieving much more than scoring a try or two will be a minor miracle.