Had a read of that document. Anyone in any shape or form of relationship can basically get out of paying any tax in Thailand. As you indicate, it would certainly be prudent to be standing next to the friend when the transaction is carried out. As it's up to 10m per year, I guess monthly "gifts" can be made too?
Illegally? Come on, this is Thailand! Over half the retirees in Thailand are on "illegal" extensions of stay courtesy of bribes paid to government officials. Come on guys, let's have a look at that 800k baht in your bank accounts! Please don't make me laugh! And do you know it's illegal to export f*ke (oops, I mean replica) handbags, watches, running shoes? Telling me it's "illegal" to not report cash brought into the country has got to be the LOL of the year!
I was using that as an example. I don't know his home country tax rates, neither do you, so you're guessing as well. So let's just say he legally transfers 150k per year, and all other money he brings as cash. So again, zero assessable income