RA2 has no connection to the Tiberium universe, so the extreme amount of crazy tech in RA2 isn't a problem in that sense; Westwood themselves even stated that RA2, although following on from RA1, takes place in its own separate universe where the world took a very different turn from that of the Tiberium universe. Both timelines canonically follow the Allied victory (with the Soviet campaign as a non-canon 'what-if' scenario), but something about the war itself or its aftermath was drastically altered to produce the RA2 timeline.
In fact, according to Westwood's internal drafts for Tiberian Incursion which EA later developed (albeit heavily changed/reworked) into C&C3, the RA2 universe was directly caused by time-travel shenanigans involving Yuri, similarly to how RA1 and the Tiberium timeline were caused by Einstein's time-travel shenanigans in the first place, making RA2 an 'alternate-alternate' universe. (Which is kinda funny since RA3 was also caused by time-travel shenanigans, making it an 'alternate-alternate-alternate' universe, with the general pattern seemingly being that every time history is changed, the world just gets progressively crazier )