Nearly every source on that word I get from Google uses that same Griffith's translation.
What does यजमानमार्यं mean?
यजमान a. [यज्-शानच्] Sacrificing, worshipping. -नः 1 A person who performs a regular sacrifice and pays its expenses; जगाम यज्वा यजमानलोकम् R.18.12; ततः प्रविशति कुशानादाय यजमानशिष्यः Ś. -2 A person who employs a priest or priests to sacrifice for him. -3 (Hence) A host, patron, rich man. -4 The head of a family. -5 The head of a tribe. -Comp. -शिष्यः the pupil of a sacrificing Brāhmaṇa (of one who himself performs a sacrifice);
मार्य - मृ 6 Ā. (but P. in the Perfect, the two Futures and the Conditional) (म्रियते, ममार, अमृत, मरिष्यति, मर्तुम्, मृत) To die, perish, decease, depart from life. -Caus. (मारयति-ते) To kill, slay. -Desid. (मुमूर्षति) 1 To wish to die. -2 To be about to die, be on the point of death.
So the correct translation would be "suicidal worshiper" - meaning he wanted to slay Indra's enemies and be martyred in the process and not "Aryan worshiper"?
I too studied Sanskrit in high school but it's almost 9 years now. My knowledge is rusty/