Imperial Resource sentials sounds better for an organization not a space marine chapter
Ehh. There's plenty of Chapters across the Galaxy with their own distinct cultures. I wouldn't be surprised if there's Chapter, which name is just series of numbers, because the Chapter is very close with Mechanicus.
Also, they are Warband, not Loyal Chapter, but
The Damned Company of Lord Caustos, shows that groups of Marines can name themselves, fairly long and unusual names.
Also, I fail to see, why Grimm supposed to go mad or why, this is giving "our kids" a bad name. The Chapter most likely decides their name, all the Grimm does is prepare Chapter resources and choose the first recruits for him to turn into the Marines and the guy who will became the Chapter Master. We know this is a joke name, but in-universe people have no idea that something like IRS existed in the first place, nor will understand the significance, for them it will be just unusual Chapter name, nothing more.
No offence
@gamer50018 but I think you and others are seriously overreacting, especially when the entire plan that started this Chapter, was a IRS joke in the first place.