LTC3780 Test load for adjusting current limit
Check the current. The maximum current thru the resistor is (30 V)/(4.7 &Omega;) = 6.4 A.  Since your supply can source 7 A, there should be no problem here.

Check the power.  The dissipation is (30 V)2/(4.7 &Omega;) = 191 W.  Oops, that's too much for a 50 W resistor.

So no, this is not "safe", if you mean safe is sticking to all the worst case limits.