Yes, for a Republican it definitely looks bad.
Everybody expects the scumbag Democrats to lie, so it's a meaningless exercise to expose them. The only thing exposing another lying Democrat does is elicit a shrug and (maybe) a sheepish grin from the lying Democrat, and cricket noises from their "mainstream" newsrooms. Then it's all quickly forgotten. But Republicans - - and especially, conservatives - - are deservedly held to a much higher standard than the scumbag Democrats. Sure, it's a "double standard", but it's one that a seasoned Republican politician like Ryan should have had ingrained in him long ago. And it's something to be proud of, not whine about, as some Republicans like to do.
That said, your "marathon runner" friends are obviously serious runners, and it is therefore understandable that they would remember exact times and other details. Ryan, who is clearly NOT a serious marathon runner, ran one marathon 22 years ago. (The fact that he was never a serious runner is demonstrated, ironically, by his reckless guess at what his time was for that run.) I do not believe Ryan lied for advantage - - really, how many people even know what a good marathon time is? - - but rather because he simply didn't want to admit he didn't know what his time was.
FRegards,
LH