If uncertain what an average (ie, per-mile) pace is going to be, whether it be with cycling or running, I've generally inquired. More important to know there's a true match, if with folks whose pace and/or ability is in question. As appears to have been the case here. They were clearly expecting a hard ride (not an 'endurance-paced' one) at a hard pace, despite having invited someone along who wasn't part of the normal group (on such a ride).

I tend to be fairly disrespecting of the slam-'em-and-leave-'em approach when others have been invited to join. IMO, so a given ride or run happens to be somewhat less-aggressively done versus expectations ... someone has been invited to join, and that's pretty much it. In running, I too have joined up with many folks where there were some differences in skills, but if billed as a given level of difficulty or distance we stuck to that and didn't push that on anyone. That's me. Though I appreciate not everyone's like that, out there.

I wouldn't get to cranked over it. There was a mismatch, in abilities (at that distance+pace) and expectations. Consider it a good example of what questions to ask next time, if joining a group where you're uncertain of its abilities and/or expectations.