It has been noted that TEC Loyalist are poor at the offense.
Now with you both being TEC Loyalists, that means that the attacker is at a considerable disadvantage.
As you noted, his attacks were not more successful as yours.
Although being somewhat underpowered compared to the TEC Rebels TEC Loyalist still are not to be underestimated when you are forced to fight on their terms. Digging in in desperate situations is where they shine.... if not in much else. A intelligently designed defense grid can be a wall of steel that can shatter the forces of two players.
It is just so that in most games TEC Loyalist never make it that far.... respectivly have no choke point to abuse and so any smart human will simple flyby and kill the rest of their worlds and then culture kill the one fortress world they could afford. If the just dont steamroll it later....
In your case I see the following options:
1. Novalith him... no doubt he can repay you but with you having more worlds you can sustain a WMD duel far longer.
2. Force him to go offensive..... dont attack him anymore.... let him attack you... preferably in conjunction with Novalith fire..... soon he will have no money left to go offensive.....
3. Prepare for a slugfest.... even without money those wall of steel is still there. Expect severe losses but if he has no money to rebuild is fleet his fate is sealed. It might take a while though.
On the note of 70 bombers not being enough..... seriously... you want to make bombers even more powerful than they are currenty?
Besides.. play Vasari.... 70 squadrons of HOLYOPPhaseMissilebombers will kill about anything in 1 or 2 passes.