Quote:
In my quickly executed research I was only able to find one comment about a person having an issue with putting a living president on a coin
Because it wasn't an issue. Living presidents haven't been putting themselves on coins or banknotes. Now one wants to, it's an issue, and people will make their opinion based on history or political beliefs.
In 1866 they had the Thayler Amendment which was made because Spencer Clark (of all people) put his own face on US banknotes. Though maybe this didn't cover coins, because they probably thought nobody would do it. However the spirit is there and has only been broken like six times.

Presidents didn't get on coins until Lincoln in 1909 with the
Lincoln Cent.
The US
Presidential dollar series said they had to be dead two years to get in the series.
https://www.thesprucecrafts.com/onl...coins-768852Governor T.E. Kilby on the front of the 1921
Alabama Centennial.
President Calvin Coolidge on the front of the 1926 Sesquicentennial of American Independence.
Senator Carter Glass on the front of the 1936 Lynchburg, Virginia, Sesquicentennial coin.
Senator Joseph T. Robinson on the back of the 1936 Robinson-Arkansas Centennial coin.
Eunice Kennedy Shriver on the obverse of the 1995 Special Olympics World Games Commemorative Silver Dollar.
Nancy Reagan on the 2016 First Spouse $10 Gold Coin.
Note: Nancy Reagan died on March 6, 2016, before the coin was officially released on July 1, 2016. However, the coin was approved and minted by The United States Mint before her death.
So, only six people, and only one of those was a president.
The law is a little dodgy, but the precedent is clear. Trump doesn't care, which is probably why this is going to be so controversial.