Sort of off topic here. This thread reminded my of a crash I saw long ago, like a new Mori sl-2 ago.
Guy from England was visiting the owner's son, who was sort of a dummy. In the shop we were all kids and the visitor was a pretty nerdy english home shop hobbyist sort so we were getting a kick out of watching him. He'd never seen a cnc lathe run so the boss told Brent, the guy setting the thing up, to press the green button and show the little guy what it woud do. Brent said it wasn't set up yet. The son said awww go ahead and show him what it will do. This went back and forth several several times until boss's son finally told Brent to "just push the goddamn button". Brent closed the door and pushed the GD button. The cycle started and the indexable drill came down and crashed right into the chuck. The little british guy musta did a personal best vertical jump. Brent turned to the Brit and in a deapan said "what did you think of that?" Boss's son just stood there like a dummy. We all howled. Like I said we were all kids and we were so proud of Brent.
Luckily no blood on the floor but ruined tooling and misaligned machine. And a shamed boss's son.
Now for the on-topic rest of the story. Guy in power was a dummy and put the operator/programmer in a bad spot, just like this idiot instructor. Hopefully nobody will get hurt. Or better yet he will see reason.
It has been my long experience running HSS endmills in mild steel w/o flood coolant just mist or brushed on that much over 100 SFM and tool life goes to hell in a hurry. That has only been on manual stuff. Never have used or very, very sedlom used HSS in the CNC's. Out of curiosity I googled HSS endmill speeds and feeds. For 1/2" 2 flute em slotting 300 BHN alloy steel .25 deep regal cutting tools suggests 360 SFM and 11 IPM. Chip load sound reasonable to low but that SFM is crazy high and 300 BHN is not mild steel territory either. That is carbide speed. Maybe the instructor got his info from some chart like this, or maybe a forum somewhere. Lots of bad info out there! Or maybe he has SFM and RPM mixed up. I don't have a machining center anymore but if I did I'd try the regal recommendation. It's not inherently dangerous and now I'm really curious if it would work for any amount of time at all.