Im not going to make any comment on the artistic quality, but FWIW he didn't ask me regarding use of the ORL graphics. Although most are not mine obviously, I am somewhat of a custodian for them through ORL and WIN, for which they were produced.
That said, all had permission for inclusion in the ORL addon, and this is clearly meant for that, so its not the worst crime. Not like they are being masqueraded as anything else but what they were designed for.
As a rule I encourage more addons and use of open source stuff, which ORL essentially is. But, shuttlecolumbia, it is considered proper within the orbiter community to ask permission if you are using other people's stuff, or at the least to include credit in the addon description/documentation.