I'm telling you, that will ruin smaller games.
Consider. 4 Vs 4; Volcano. SBH plants nuke at the back of the Rax. A patch leaving the PP hears the beacon sound and investigates, finds and kills the SBH, then has to go back inside the PP or Rax, then get a hotty then come out and TIMES UP! BOOM! rax explodes. Whereas, if he could get a PT through the wall, he would've saved the bar. (assuming the other three team members, who probably should've been a med, hotty and sniper came back to help, they'd still be late, esp. if Nod attacks them on thier way back)
At least consider making it a serverside option.