I wouldn't worry about VSWR too much since this kind of termination is always a compromise (but much better than no termination at all), since there is significant length of unterminated stub behind the terminator when connected to a typical scope, so I doubt if it makes any difference at all if VSWR is 1.01 (return loss 46 dB) or 1.3 (return loss 17.7 dB) for the terminator itself. For this reason, higher bandwidth scopes have a terminator resistor built in, so that the unterminated stub length is greatly reduced.
Regards,
Janne